document.write( "Question 1194404: A survey of 130 pet owners yielded the following information: 47 own fish; 53 own a bird; 50 own a cat; 64 own a dog; 2 own all four; 11 own only fish; 14 own only a bird; 10 own fish and a bird; 21 own fish and a cat; 24 own a bird and a dog; 27 own a cat and a dog; 3 own fish, a bird, a cat, and no dog; 1 owns fish, a bird, a dog, and no cat; 9 own fish, a cat, a dog, and no bird; and 10 own a bird, a cat, a dog, and no fish. How many of the surveyed pet owners have no fish, no birds, no cats, and no dogs? (They own other types of pets.) \n" ); document.write( "
Algebra.Com's Answer #826612 by math_tutor2020(3817)\"\" \"About 
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\n" ); document.write( "A = person owns a fish
\n" ); document.write( "B = person owns a bird
\n" ); document.write( "C = person owns a cat
\n" ); document.write( "D = person owns a dog\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "There are 4 pets, so there are 2^4 = 16 different possibilities.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Here are the 16 possibilities
  1. Person doesn't own any of the four pets mentioned
  2. A - persons owns a fish only
  3. B - they own a bird only
  4. C - owns a cat only
  5. D - owns a dog only
  6. AB - fish and bird only
  7. AC - fish and cat only
  8. AD - fish and dog only
  9. BC - bird and cat only
  10. BD - bird and dog only
  11. CD - cat and dog only
  12. BCD - bird, cat, and dog (i.e. everything but a fish)
  13. ACD - fish, cat and dog (i.e. everything but a bird)
  14. ABD - fish, bird and dog (everything but a cat)
  15. ABC - fish, bird and cat (everything but a dog)
  16. ABCD - person owns all four pets mentioned

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\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Let's draw out the Venn Diagram.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Start by drawing two ovals like so. Make sure they overlap.
\n" ); document.write( "
\n" ); document.write( "Create a mirror copy of those two ovals to have a total of four ovals.
\n" ); document.write( "
\n" ); document.write( "Then slide the ovals over until we get this
\n" ); document.write( "
\n" ); document.write( "It may seem like a bit of a mess, so be sure you can break apart the various ovals (or be able to spot the four ovals).
\n" ); document.write( "This is why I recommend following these steps to slide the ovals over.
\n" ); document.write( "Unfortunately we can't have the ovals separated or else we won't be able to form the overlapped regions needed.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Next, we'll add the 15 labels mentioned in the previous section above. The first label of \"none of the 4 pets mentioned\" is ignored for now, as it goes outside the four ovals.
\n" ); document.write( "
\n" ); document.write( "Color-coding things helps us separate the various regions (it may be easy to get lost)
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\n" ); document.write( "
  • Regions in white are for the people who own exactly one pet only
  • Regions in blue are for the people who own exactly two pets only
  • Regions in red are for the people who own exactly three pets only
  • The region in green is for the people who own all four pets mentioned
\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Take note how something like region ABC is in ovals A, B and C at the same time. Region ABC is outside oval D.
\n" ); document.write( "Similar logic applies to how the other regions are set up.
\n" ); document.write( "The region outside the ovals represents people who own none of the four pets mentioned.\r
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\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Let's fill out the Venn Diagram with numeric values.\r
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\n" ); document.write( "\n" ); document.write( "To do so, we'll need to use the given facts:\n" ); document.write( "\n" ); document.write( "
NumberStatement
147 own fish
253 own a bird
350 own a cat
464 own a dog
52 own all four
611 own only fish
714 own only a bird
810 own fish and a bird
921 own fish and a cat
1024 own a bird and a dog
1127 own a cat and a dog
123 own fish, a bird, a cat, and no dog
131 owns fish, a bird, a dog, and no cat
149 own fish, a cat, a dog, and no bird
1510 own a bird, a cat, a dog, and no fish
\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "We start with statement 5, which says \"2 own all four\"
\n" ); document.write( "This number goes inside the region labeled ABCD.
\n" ); document.write( "In other words, this number goes in the region that is inside all four ovals.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Now move onto statement 6. It says \"11 own only fish\", which means 11 goes in the region labeled \"A\".
\n" ); document.write( "This is the region inside oval A, but outside any other oval.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Now onto statement 7. It says \"14 own only a bird\", so we'll write \"14\" in region B. This is the region inside oval B, but outside any other oval.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Let's jump ahead to statement 12.
\n" ); document.write( "It says \"3 own fish, a bird, a cat, and no dog\".
\n" ); document.write( "We'll write the number 3 inside the region labeled \"ABC\".
\n" ); document.write( "This is the region inside ovals A,B,C but outside oval D.
\n" ); document.write( "To be more accurate, I'll write it off to the side since region ABC is very small.
\n" ); document.write( "I'll be doing the same with regions ABD, AC and BD as well.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "The next statement (statement 13) says \"1 owns fish, a bird, a dog, and no cat\"
\n" ); document.write( "The number \"1\" goes with region ABD.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Up next is the statement \"9 own fish, a cat, a dog, and no bird\" (statement 14). It tells us that the number 9 goes inside region ACD.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Up next is the statement \"10 own a bird, a cat, a dog, and no fish\" (statement 15).
\n" ); document.write( "It tells us that the number 10 goes inside region BCD.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Here's a mini recap so far:
\n" ); document.write( "A = 11
\n" ); document.write( "B = 14
\n" ); document.write( "ABC = 3
\n" ); document.write( "ABD = 1
\n" ); document.write( "ACD = 9
\n" ); document.write( "BCD = 10
\n" ); document.write( "ABCD = 2
\n" ); document.write( "That takes care of 7 regions, so there are 16-7 = 9 more to go.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "This is what your Venn Diagram should look like at this point (after filling in the proper regions)
\n" ); document.write( "\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "We'll move to statement 8 now.
\n" ); document.write( "It says \"10 own fish and a bird\"
\n" ); document.write( "Use a pen tool to highlight oval A and oval B as shown below.
\n" ); document.write( "
\n" ); document.write( "The two ovals highlighted overlap in this teardrop shaped region marked below
\n" ); document.write( "
\n" ); document.write( "Everything in this teardrop region is in oval A and oval B at the same time. The subregions involved in this teardrop are:
\n" ); document.write( "Region AB
\n" ); document.write( "Region ABC
\n" ); document.write( "Region ABD
\n" ); document.write( "Region ABCD
\n" ); document.write( "Each of the four strings starts with \"AB\", and we either leave it as is, or we tack on various combos of C and/or D.
\n" ); document.write( "This is a methodical way to list out all the possibilities of someone owning a fish and a bird (and possibly a cat and/or dog).\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Algebraically we can form the equation
\n" ); document.write( "AB+ABC+ABD+ABCD = 10
\n" ); document.write( "since 10 people own a fish and a bird (and possibly a cat and/or dog).\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Be careful and try not to think about something like \"ABC\" as \"A*B*C\".
\n" ); document.write( "ABC is one variable name, and not the product of three separate variables.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "We'll apply the following substitutions
\n" ); document.write( "ABC = 3
\n" ); document.write( "ABD = 1
\n" ); document.write( "ABCD = 2
\n" ); document.write( "to go from this
\n" ); document.write( "AB+ABC+ABD+ABCD = 10
\n" ); document.write( "to this
\n" ); document.write( "AB+3+1+2 = 10
\n" ); document.write( "and it solves to
\n" ); document.write( "AB = 4
\n" ); document.write( "This says \"4 people have a fish and a bird, but not a cat and not a dog\".
\n" ); document.write( "That was all for statement 8. \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Now onto statement 9.
\n" ); document.write( "We'll have this equation
\n" ); document.write( "AC+ABC+ACD+ABCD = 21
\n" ); document.write( "Each item on the left hand side has \"A\" and \"C\" in it somewhere.
\n" ); document.write( "Plug in these items
\n" ); document.write( "ABC = 3
\n" ); document.write( "ACD = 9
\n" ); document.write( "ABCD = 2
\n" ); document.write( "to go from this
\n" ); document.write( "AC+ABC+ACD+ABCD = 21
\n" ); document.write( "to this
\n" ); document.write( "AC+3+9+2 = 21
\n" ); document.write( "which solves to
\n" ); document.write( "AC = 7
\n" ); document.write( "Therefore, 7 people have a fish and a cat, but none of the other two mentioned pets.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Onto statement 10.
\n" ); document.write( "We'll have this equation
\n" ); document.write( "BD+ABD+BCD+ABCD = 24
\n" ); document.write( "Each item on the left hand side has \"B\" and \"D\" in it somewhere.
\n" ); document.write( "Plug in these items
\n" ); document.write( "ABD = 1
\n" ); document.write( "BCD = 10
\n" ); document.write( "ABCD = 2
\n" ); document.write( "to go from this
\n" ); document.write( "BD+ABD+BCD+ABCD = 24
\n" ); document.write( "to this
\n" ); document.write( "BD+1+10+2 = 24
\n" ); document.write( "which solves to
\n" ); document.write( "BD = 11
\n" ); document.write( "Therefore, 11 people have a bird and a dog, but none of the other two mentioned pets.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Onto statement 11.
\n" ); document.write( "We'll have this equation
\n" ); document.write( "CD+ACD+BCD+ABCD = 27
\n" ); document.write( "Each item on the left hand side has \"CD\" in it.
\n" ); document.write( "Plug in these items
\n" ); document.write( "ACD = 9
\n" ); document.write( "BCD = 10
\n" ); document.write( "ABCD = 2
\n" ); document.write( "to go from this
\n" ); document.write( "CD+ACD+BCD+ABCD = 27
\n" ); document.write( "to this
\n" ); document.write( "CD+9+10+2 = 27
\n" ); document.write( "which solves to
\n" ); document.write( "CD = 6
\n" ); document.write( "Therefore, 6 people have a cat and a dog, but none of the other two mentioned pets.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Let's update that previous recap:
\n" ); document.write( "ABCD = 2
\n" ); document.write( "A = 11
\n" ); document.write( "B = 14
\n" ); document.write( "ABC = 3
\n" ); document.write( "ABD = 1
\n" ); document.write( "ACD = 9
\n" ); document.write( "BCD = 10
\n" ); document.write( "AB = 4
\n" ); document.write( "AC = 7
\n" ); document.write( "BD = 11
\n" ); document.write( "CD = 6

\n" ); document.write( "The new items are in red.\r
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\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Go back to the top to statement 1.
\n" ); document.write( "47 people own a fish. Some of these 47 people own a fish only, while others may own exactly one other pet along with the fish, or two other pets along with the fish, or own all 4 pets mentioned.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "A = fish owners only
\n" ); document.write( "AB = fish + bird
\n" ); document.write( "AC = fish + cat
\n" ); document.write( "AD = fish + dog
\n" ); document.write( "ABC = fish + bird + cat
\n" ); document.write( "ABD = fish + bird + dog
\n" ); document.write( "ACD = fish + cat + dog
\n" ); document.write( "ABCD = all four pets mentioned
\n" ); document.write( "It may help to use your pen tool to circle all of oval A.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "We have the following values:
\n" ); document.write( "A = 11 (given from statement 6)
\n" ); document.write( "AB = 4 (solved earlier; see statement 8)
\n" ); document.write( "AC = 7 (solved earlier; see statement 9)
\n" ); document.write( "AD = unknown, we'll be solving for it soon
\n" ); document.write( "ABC = 3 (solved earlier; see statement 12)
\n" ); document.write( "ABD = 1 (solved earlier; see statement 13)
\n" ); document.write( "ACD = 9 (solved earlier; see statement 14)
\n" ); document.write( "ABCD = 2 (given; see statement 5)\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "These values must add up to the 47 fish owners
\n" ); document.write( "A+AB+AC+AD+ABC+ABD+ACD+ABCD = 47
\n" ); document.write( "11+4+7+AD+3+1+9+2 = 47
\n" ); document.write( "AD+37 = 47
\n" ); document.write( "AD = 47-37
\n" ); document.write( "AD = 10
\n" ); document.write( "There are 10 people who have a fish and a dog, but no other pet mentioned.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Move onto statement 2, which says \"53 own a bird\".
\n" ); document.write( "We'll circle the regions that involve the letter B in some fashion, i.e. we'll circle all of oval B.
\n" ); document.write( "B = bird owners only
\n" ); document.write( "AB = fish + bird
\n" ); document.write( "BC = bird + cat
\n" ); document.write( "BD = bird + dog
\n" ); document.write( "ABC = fish + bird + cat
\n" ); document.write( "ABD = fish + bird + dog
\n" ); document.write( "BCD = bird + cat + dog
\n" ); document.write( "ABCD = all four pets mentioned\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "We'll be using these values to help solve for variable BC
\n" ); document.write( "B = 14 (given; see statement 7)
\n" ); document.write( "AB = 4 (solved earlier; see statement 8)
\n" ); document.write( "BD = 11 (solved earlier; see statement 10)
\n" ); document.write( "ABC = 3 (solved earlier; see statement 12)
\n" ); document.write( "ABD = 1 (solved earlier; see statement 13)
\n" ); document.write( "BCD = 10 (solved earlier; see statement 15)
\n" ); document.write( "ABCD = 2 (given; see statement 5)\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So,
\n" ); document.write( "B+AB+BC+BD+ABC+ABD+BCD+ABCD = 53
\n" ); document.write( "14+4+BC+11+3+1+10+2 = 53
\n" ); document.write( "BC = 8
\n" ); document.write( "There are 8 pet owners that have a bird and a cat, but no other pets mentioned.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Now onto statement 3.
\n" ); document.write( "Circle oval C, i.e. circle each region that involves C in some way
\n" ); document.write( "C = cat only
\n" ); document.write( "AC = fish and cat only
\n" ); document.write( "BC = bird and cat only
\n" ); document.write( "CD = cat and dog only
\n" ); document.write( "ABC = fish + bird + cat
\n" ); document.write( "ACD = fish + cat + dog
\n" ); document.write( "BCD = bird + cat + dog
\n" ); document.write( "ABCD = all four pets mentioned\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "We have the following values:
\n" ); document.write( "AC = 7 (solved earlier in statement 9)
\n" ); document.write( "BC = 8 (solved earlier in statement 2)
\n" ); document.write( "CD = 6 (solved earlier in statement 11)
\n" ); document.write( "ABC = 3 (see statement 12)
\n" ); document.write( "ACD = 9 (see statement 14)
\n" ); document.write( "BCD = 10 (see statement 15)
\n" ); document.write( "ABCD = 2 (see statement 5)\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "So,
\n" ); document.write( "C+AC+BC+CD+ABC+ACD+BCD+ABCD = 50
\n" ); document.write( "C+7+8+6+3+9+10+2 = 50
\n" ); document.write( "C+45 = 50
\n" ); document.write( "C = 50-45
\n" ); document.write( "C = 5
\n" ); document.write( "There are 5 people who own a cat only (and none of the other three pets mentioned).\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Now onto the last statement left, which is statement 4.
\n" ); document.write( "There are 64 people who own a dog which means,
\n" ); document.write( "D+AD+BD+CD+ABD+ACD+BCD+ABCD = 64
\n" ); document.write( "D+10+11+6+1+9+10+2 = 64
\n" ); document.write( "D+49 = 64
\n" ); document.write( "D = 64-49
\n" ); document.write( "D = 15
\n" ); document.write( "There are 15 dog owners who do not have a fish, nor a bird, nor a cat.\r
\n" ); document.write( "
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\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Here's the complete summary of what we found
\n" ); document.write( "A = 11
\n" ); document.write( "B = 14
\n" ); document.write( "C = 5
\n" ); document.write( "D = 15
\n" ); document.write( "AB = 4
\n" ); document.write( "AC = 7
\n" ); document.write( "AD = 10
\n" ); document.write( "BC = 8
\n" ); document.write( "BD = 11
\n" ); document.write( "CD = 6
\n" ); document.write( "ABC = 3
\n" ); document.write( "ABD = 1
\n" ); document.write( "ACD = 9
\n" ); document.write( "BCD = 10
\n" ); document.write( "ABCD = 2
\n" ); document.write( "This is what the completed Venn Diagram looks like
\n" ); document.write( "
\n" ); document.write( "The 14 outside of all of the ovals is the final answer and explained in the next two paragraphs.\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Add up all of those values to find out how many people there are that own at least one of the four pets mentioned.
\n" ); document.write( "A+B+C+D+AB+AC+AD+BC+BD+CD+ABC+ABD+ACD+BCD+ABCD
\n" ); document.write( "11+14+5+15+4+7+10+8+11+6+3+1+9+10+2
\n" ); document.write( "116\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "There are 116 people who have at least one pet of the four pets mentioned.
\n" ); document.write( "There are 130 people total.
\n" ); document.write( "That must mean there are 130-116 = 14 people who do not have any of the four pets mentioned.\r
\n" ); document.write( "
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\n" ); document.write( "\n" ); document.write( "Final Answer: 14
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