document.write( "Question 1179299: A well driller charges $9.00 per foot for the first 10 feet, $9.10 per foot for the next 10 feet, $9.20 per foot for the next 10 feet, and so on, at a price increase at $0.10 per foot for succeeding intervals of 10 feet. How much does it cost to drill a well to a depth of 150 feet?
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Algebra.Com's Answer #808844 by ikleyn(52803) $\"\"$ $\"About$

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\n" ); document.write( "A well driller charges $9.00 per foot for the first 10 feet, $9.10 per foot for the next 10 feet,
\n" ); document.write( "$9.20 per foot for the next 10 feet, and so on, at a price increase at $0.10 per foot for succeeding
\n" ); document.write( "intervals of 10 feet. How much does it cost to drill a well to a depth of 150 feet?
\n" ); document.write( "We need to solve this by using some sort of sequence and its equation. Thank you
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document.write( "The depth of 150 ft is 10 times taken the depth of 15 feet.\r\n" );
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document.write( "So the person shoud pay $9.00  per first 15 ft;\r\n" );
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document.write( "                   then $9.10  per next  15 ft;\r\n" );
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document.write( "                   then $9.20  per next  15 ft;\r\n" );
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document.write( " . . . . . . . . . . . . . . . . . . . . . . . . \r\n" );
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document.write( "                   and so on until $10.40 per the last 15 ft.\r\n" );
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document.write( "Thus uou need to find the sum \r\n" );
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document.write( "    9.00 + 9.10 + 9.20 + . . . + 10.40  dollars.\r\n" );
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document.write( "This sequense is an arithmetic progression with the first term equal to 9.00;\r\n" );
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document.write( "with the common difference of 0.10 and the number of terms 15.\r\n" );
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document.write( "There are different formulas and several ways to find the sum.\r\n" );
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document.write( "          The simplest way for beginner students is to find \r\n" );
document.write( "          the average value of the progression and multiply it \r\n" );
document.write( "          by the number of terms in the progression.\r\n" );
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document.write( "In this case, the average value of the progression is half the sum of the first and the last terms \r\n" );
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document.write( "     =  =  = 9.70  dollars;\r\n" );
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document.write( "So the total cost (the sum) is  9.70*15 = 145.50 dollars.\r\n" );
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document.write( "ANSWER.  $145.50.\r\n" );
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\n" ); document.write( "\n" ); document.write( "For introductory lessons on arithmetic progressions see \r
\n" ); document.write( "\n" ); document.write( "    - Arithmetic progressions\r
\n" ); document.write( "\n" ); document.write( "    - The proofs of the formulas for arithmetic progressions \r
\n" ); document.write( "\n" ); document.write( "    - Problems on arithmetic progressions \r
\n" ); document.write( "\n" ); document.write( "    - Word problems on arithmetic progressions\r
\n" ); document.write( "\n" ); document.write( "in this site.\r
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\n" ); document.write( "\n" ); document.write( "Also, you have this free of charge online textbook in ALGEBRA-II in this site\r
\n" ); document.write( "\n" ); document.write( "    - ALGEBRA-II - YOUR ONLINE TEXTBOOK.\r
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\n" ); document.write( "\n" ); document.write( "The referred lessons are the part of this online textbook under the topic \"Arithmetic progressions\".\r
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\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Save the link to this textbook together with its description\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Free of charge online textbook in ALGEBRA-II
\n" ); document.write( "https://www.algebra.com/algebra/homework/complex/ALGEBRA-II-YOUR-ONLINE-TEXTBOOK.lesson\r
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\n" ); document.write( "\n" ); document.write( "into your archive and use when it is needed.\r
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