# Questions on Algebra: Average answered by real tutors!

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Question 817524: The average for 10 girls in the math class was 30 out of 40.
The average for 15 boys was also 30 out of 40. Which group did the best?

You can put this solution on YOUR website!
g:
30/40
3/4
0.75
g = 75%
---
b:
30/40
3/4
0.75
b = 75%
---
g = b
both groups they did exactly the same, neither group was best.
---
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Question 817448: The grading scale for a C in Amy's biology class is an average on tests between 70% and 80%, inclusive. Amy has 64%,84%,and 78%on the first three tests this semester. What range of scores on the fourth test would give her a C?
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( 64 + 84 + 78 + x )/4 >= 70 is the equation for obtaining at least a C
( 226 + x )/4 >= 70
Multiply each side by 4
226 + x >= 70*4
226 + x >= 280
Subtract 226 from each side.
x >= 54
To determine the maximum value of x
we need to solve
( 64 + 84 + 78 + x )/4 <= 80
The rest is left for the student.

Question 817392: What is 88 if you take out 75%

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```
Hi,
What is 88 if you take out 75% 0r

88 - 66 = 22 is what is left after taking out 75% 0r  of it
Problem can also be done as follows:
,  88-66 = 22
```

Question 817232: If I have an average of a 72 and I will take a test that's worth 20%. What grade do I need to get on my test in order for my average to be 80 or above?

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if the test is worth 20% then the present average is worth 80%
.80*72+.2x>=80
57.6 +.2 x>=80
your 72 average is only worth 57.6 you need to get 20% of the test that is worth 22.4
You will need to get 112 on the test
to get 75 you will need 87
with a grade of 100 on the test you would get a total 77.6

Question 817194: if the average (arithmetic mean) of a series of numbers is 20, and the sum of these numbers is 160, how many numbers are in the series?
You can put this solution on YOUR website!
if the average (arithmetic mean) of a series of numbers is 20, and the sum of these numbers is 160, how many numbers are in the series?
------
If there are n numbers and their mean is 20, sum/n = 20
sum = 160
-------
Equation:
20n = 160
n = 8 (# of numbers in the series)
---------------------------------------
Cheers,
Stan H.
===========

Question 817110: Tom multiplied a number by 3/2 to get 50, but he should have divided the number by 3/2 to get the correct answer. What is the correct answer?
You can put this solution on YOUR website!

let's a number be
if Tom multiplied a number by to get , we have
............solve for

but, if he should have divided the number by to get the correct answer will be

Question 817068: the average of 6 nos. is 23 if the average of first 3 nos. is 22 what is the average of last 3 nos.
You can put this solution on YOUR website!
the average of 6 nos. is 23 if the average of first 3 nos. is 22 what is the average of last 3 nos.
----------
The sum of the 6 is 6*23 = 138
The sum of the 1st 3 is 3*22 = 66

Question 817051: Cris answered 61 out of 66 questions correctly on a test. What is his test average to the nearest thousandth
You can put this solution on YOUR website!
Divide 61/66
.92424242424242
Bring decimal over two places
92.4242
The 2nd 4 is the thousandth place.
Cris' score would be 92.424%

Question 816929: If my semester average now is 61, finals are worth 10% percent of my grade. What will I need to make on my final to make a 70?
You can put this solution on YOUR website!
(0.9)61 + (0.1)X = 70 will give us the grade needed to have an average
of exactly 70
54.9 + 0.1x = 70
Subtract 54.9 from each side.
0.1x = 70 - 54.9
0.1x = 15.1
x = 151
So we need a score of 151 on the final to have an average of 70.

Question 816936: Ok, quiz question of the day!! If there are 150 questions on a test and the end score needed is a 75 out of 100, how many answers can I get wrong??
You can put this solution on YOUR website!
You could solve by proportion.

Cross products gives us
100x = 11250
x = 112.50
Here we have solved for the number that we need right,
so the number we can miss is 150 - 112.50 = 37.50 .

Question 816737: Aura took three biology exams and has an average score of 87. Her second exam score was 7 points better than her first, and her third exam score was 1 points better than her second exam. What were her three exam scores?
You can put this solution on YOUR website!
```
Hi,
Her second exam score was 7 points better than her first,
and her third exam score was 1 points better than her second exam.
1st Exam  x
2nd Exam  x +7
3rd Exam  x + 8
average score of 87:  Total points for the 3 exams = 261
x + (x+7) + (x+8) = 261    |Solve for x
3x = 246
x = 82
1st Exam  x           82
2nd Exam  x +7        89
3rd Exam  x + 8       90

```

Question 816673: If 85% of the years tests are over and my average is 63%, and my end of year exam is worth 15% of my grade, what score do I need to keep my average at 63%
You can put this solution on YOUR website!
the formula is:
.85 * 63% + .15 * x = 63%
solve for x to get:
x = (63% - .85*63%) / .15 which results in:
x = 63%

if you want to raise your score to 65%, then the formula would be:
.85 * 63% + .15 * x = 65%
solve for x to get:
x = (65% - .85 * 63%) / .15 which results in:
x = 76.333333333%

the best you can do is if you get 100% on the final.
then your overall average would be:
.85 * 63% + .15 * 100% = 68.55%

Question 816596: The mean score on a set of 20 tests is 75. What is the sum of the 20 test scores?

Question 816513: What is the average of 130 and 68
You can put this solution on YOUR website!
What is the average of 130 and 68
----------
There are 2 elements.

Question 816447: Is it possible for 10 out of 10 students to score above average on a test?
You can put this solution on YOUR website!
No
---
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Question 816337: If handwriting size was 1.5 millimeters for 4 subjects and 4 millimeters for 3 subjects, what is the average handwriting size for all 7 subjects?
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( 1.5*4 + 4*3 ) / 7 = 2.57 mm
---
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---
---
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Question 816253: Trying to figure out what I need to make on final to pass my class.
Test average 75
Hw Average 100
Final ?
Test average worth 60%
Hw average worth 15 %
Final worth 25%

You can put this solution on YOUR website!
g = ( (75/100)(0.60) + (100/100)(0.15) + (f/100)(0.25) ) * 100
g = A + (0.25)f
---
A = (75)(0.60) + (100)(0.15)
you do the math
---
f is your score in the final test, between 0 and 100
---
if you know what grade you need to pass the class, substitute that for g and solve for f
---
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---
---
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Question 816230: If I recieve \$30 worth of gift cards for \$20, what is my percentage of savings?
You can put this solution on YOUR website!
If I receive \$30 worth of gift cards for \$20, what is my percentage of savings?
---------
Amount of savings: 30-20 = \$10
----------
Percent of savings: 10/30 = 1/3 = 33 1/3%
--------------------
Cheers,
Stan H.
======================

Question 816201: If i have an average of 78% and I need an average of 80% how many marks out of 60 do i need to get in my exam? The exam is worth 25%
You can put this solution on YOUR website!
```
Hi,
have an average of 78% and I need an average of 80%,exam(60 marks) is worth 25%
Let x represent % score of final
.75*78 + .25x = 80
x =
x = 86% on final exam  and  52 marks correct
```

Question 816137: If I get 3 problems right out of 4 what average will I have

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3/4 * 100 = 75%
---
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---
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Question 816113: a final is worth 30 percent of my grade and has 100 questions what would i need to score to get a b in the course?
You can put this solution on YOUR website!

For more help from me, visit: www.algebrahouse.com

Question 815779: Jina purchased a prepaid phone card for \$25. Long distance calls cost 23 cents a minute using this card. Jina used her card only once to make a long distance call. If the remaining credit on her card is 15.57 , how many minutes did her call last?
You can put this solution on YOUR website!
(25-15.57)/0.23=41 min

Question 815743: If the average of first 101 natural numbers be 51,what is the average of 100 natural numbers?
You can put this solution on YOUR website!
If the average of first 101 natural numbers be 51,what is the average of 100 natural numbers?
-----
50.5

Question 815680: Bill gates obtained a total score of 1980 points in the three computer games. His average score was 24 points below his previous game average. What was his average score before the games.
You can put this solution on YOUR website!
```
Hi,
1980 points in the three computer games.  Average =
His average score was 24 points below his previous game average.
What was his average score before the games.
```

Question 815627: If I have an overall average of 85% in my class, and the final exam counts for 40% of my final grade, what do I need to get on my final exam to pass the class with above a 70%?
You can put this solution on YOUR website!
The final exam counts for 40% of your grade (given). So the remainder of the class assignments (hw, quizzes, etc) is 100% - 40% = 60% of your grade.

Let x = grade on the final exam

(0.40)*(x) + (0.60)*(0.85) = 0.70 ... Note: percentages are converted to decimal form

(0.40)*(x) + (0.60)*(0.85) = 0.70

0.40x + 0.51 = 0.70

0.40x = 0.70 - 0.51

0.40x = 0.19

x = 0.19/0.40

x = 0.475

So this means you need to get a 47.5% or higher on the final exam to get a 70% or higher for an overall grade.

Note: the 85% is clearly above 70% (quite significantly too), which explains why you're given so much slack and you can get such a low score on the final (and still get away with a decent grade).

Another Note: your professor may grade on a curve or have other rules for grading (such as dropping the lowest score). It's best to ask the professor directly about questions like this. However, this gives you a basic idea of what you should get.

Question 815517: Average age of 30 students in a class is 10. then 1 more is took admission in that class. now the average of their age is 11. then find the age of last one?

You can put this solution on YOUR website!
To solve this we know that,
Average of age= total ages of students/ total Students
10 = total ages of students/30
10*30= total ages of students
300= Total ages of students

Now
When 1 student is added there will be total 11 students using above formula
Average of age= Total ages of students/ total ages of students
11 = total ages of students/ 31
Total ages of students= 31*11
= 341
Change in total age= 341 - 300

Age of 11th student= 41

Question 815368: 20% of your grade depends on a test. If the test is comprised of 15 questions, all of equal weight, how much of your total grade is each question worth?
You can put this solution on YOUR website!
20 / 15 = 1.33333 = 4/3 % per question
---
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---
---
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Question 814459: I have an overall grade of 82.2 percent actually. how many points do I have to get in order to have 90 percent?
You can put this solution on YOUR website!
insufficient data...
Please repost with a clear and complete question :)

Question 815211: Your test score in science are 83 and 87. What possible scores can you earn on your next test to have a test average between 85 and 90,inclusive?
Found 2 solutions by MathTherapy, josmiceli:
You can put this solution on YOUR website!

Your test score in science are 83 and 87. What possible scores can you earn on your next test to have a test average between 85 and 90,inclusive?

```
Let 3rd score be S
Then:
255 < 170 + S < 270 ------- Multiplying by LCD, 3
255 - 170 < S < 270 - 170
85 < S < 100
The 3rd score should be between 85 and 100, non-inclusive.

You can do the check!!

Further help is available, online or in-person,for a fee, obviously.

GENERAL MATH QUESTIONS, MATH HOMEWORK QUESTIONS, or MATH QUESTIONS related to the Regents Integrated Algebra,
Regents Geometry, Regents Algebra 2/Trigonometry, SHSAT, COOP/HSPT/TACHS, PSAT, SAT, ACT, SSAT/ISEE, GRE, CLEP,
and the GED, you can visit: http://asvabstudyzone.freeforums.net/.
```

You can put this solution on YOUR website!
Let = your score on the next test
-------------
In order to have an 85 average, you need at least:

----------------
In order to have an 90 average, you need at least:

-----------------
You need to score between 85 and 100 inclusive

Question 815214: If I have a 95% in a class and my final is worth 20% what is the lowest grade I can get to keep an A
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If I have a 95% in a class and my final is worth 20% what is the lowest grade I can get to keep an A
-------------
You have to spec what % is an A.

Question 815034: Twelve students in a class average 70% on a certain test.Eighteen others average 80%.What is the overall average of the thirty students as a percent?please tell the answer....
You can put this solution on YOUR website!
```
Hi,
Twelve students in a class average 70% on a certain test.
Eighteen others average 80%.
What is the overall average of the thirty students as a percent?
= 73%
```

Question 814943: Can someone help me solve this question please!
Question:The average price of 12 goats and 12 sheep is \$600. If the price of a sheep is twice that of a goat, find the total price of 3 goats and 2sheep.

Found 2 solutions by mananth, ewatrrr:
You can put this solution on YOUR website!
goat price = x
sheep price =y
(12x+12y)/24 is the average price
(12x+12y)/24=600
12x+12y=24*600
/12
x+y=1200.......................(1)
y= 2x...........................(2)
substitute y=2x in )1)
x+2x=1200
3x=1200
x=400
y=2x
so y=800

You can put this solution on YOUR website!
```
Hi,
The average price of 12 goats and 12 sheep is \$600.
price of a sheep is twice that of a goat
Let x represent the price of a goat and 2x the price of a sheep
Question states***

Solve for x, determine 2x and then find the total price of 3 goats and 2sheep
```

Question 814945: Can someone help me solve this question please!
Question:Tom scored 85 runs in the 17th inning and thereby increased the run average of the previous 16 innings by 3. What were his average runs in 17 innings?

You can put this solution on YOUR website!
```
Hi,
Question:Tom scored 85 runs in the 17th inning
and thereby increased the run average "x" of the previous 16 innings by 3.
Question states***
Solve for x and then determine x+3
```

Question 814937: A class of 6 girls and 4 boys has an average score of 75 in a test. The girls' average was 5 higher than the boys. What was the boys' average test score?
I am stumped!

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```
Hi,
A class of 4 boys and 6 girls has an average score of 75 in a test.
The girls' average was 5 higher than the boys.
Let x represent the boy's average and (x+5) represent the girl's average
Question states***

Solving for x
10x = 750 -30
10x = 720,  x = 72, the boy's average.  The girls' average was 77

```

Question 814773: which is greater? 85% or 4/5
You can put this solution on YOUR website!
which is greater? 85% or 4/5
------------
Change 4/5 to a % and compare.

Question 814675: What's the average of 30 27 28

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(30 + 27 + 28)/3 = 28.333333
---
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---
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Question 814622: Your final exam is 25% of your final grade. You want to get 80%. Your average on ,the first 3 tests is 75. What do you need on the final to reach your goal?
You can put this solution on YOUR website!
```
Hi,
Note: 3 tests plus final 0r 4 tests each counting 25% of grade
average on the first 3 tests is 75  0r 225 point earned to date
Let x represent final exam score
If
then    x =  = 95
```

Question 814496: Can u help mi solve this problem The main average Weight ofrece 5 boys weight 152 ,158, and 168 pounds respectively which of the following could be the weight in pounds of the other 2 boya?

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not trying to be mean can you please use proper spelling so we can understand the question a bit more, also you never specified a main average so you cant work out the average of the other 2 boys..

Question 814470: Hi,can you please show me how to solve this problem? '' Shathea had quiz scores for the semester of 67, 88, 75, 93, 81, and 100''. What was the average of her test scores?
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Divide by the # of scores.

Question 814188: a student misses 7 problems on a chemistry test and received a grade of 85%. If all the problems were of equal value, how many problems were on the test?
You can put this solution on YOUR website!
((n - 7)/n) * 100 = 85
(n - 7)/n = 0.85
n - 7 = 0.85n
0.15n = 7
n = 7/0.15
n = 46.6666666
---
because a test cannot have a fractional number of questions, we round n up to the next integer, so:
n = 47
---
Check:
(40/47)*100 = 85.10638
so the teacher must have rounded the student's score to the nearest percent.
---
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Question 814152: if my final exam is worth 25% and my other 5 tests average a 93% what grade do I need on my final to average a 90% for the class
You can put this solution on YOUR website!
0.25f + 0.75(0.93) = 0.9
0.25f + 0.6975 = 0.9
0.25f = 0.2025
f = 0.81
---
you need 81% on the final
---
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---
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Question 814051: if "w" is to "y" as 6 is to 5, and their total is 88, what is "w"?

You can put this solution on YOUR website!
w/y=6/5
w=6x
y=5x
w+y=88
6x+5x=88
11x=88
x=8
w=48
y=40

Question 814008: Does the equation y=12x+28 pass through the lines (-1,16) & (5,88)