A few days ago
steve

# homework help?

i have 2 math problems that i do not understand could someone explain how to do them?

1. Before the final exam, a student has test scores of 72, 80, 65, 78, & 60. If the final exam counts as one-third of the final grade, what score must the student receive in order to have a final average of 76?

2. The cost of installing insulation in a particular 2 bedroom home is \$1080. Present monthly heating costs average \$60, but the insulation is expected to reduce heating costs by 10%. How many months will it take to recover the cost of the insulation?

A few days ago
chasrmck

1) since the final is 1/3 of the grade, these tests together are 2/3 or twice as much so just count them twice. (72+80+65+78+60)/5+(72+80+65+78+60/5+x)/3=76

(71+71+x)/3=76

142+x=228

x=86

2) x= No of months

60*x current cost

.1*60*x=1080

6x=1080

x=180mos or 15 years

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A few days ago
apathycat
For the first one you should be able to solve it using the following equation

(72+80+65+78+60)/5*2/3 + 1/3X = 76. Try it and see

The second one is easy. You are simply going to need to reduce the monthly eating cost by 10%, and divide the cost of the insulation by the result.

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A few days ago
sean m
final exam= 33%

so between the 5 other exams the most could have been 66%so add 72,80,65,78,60 and divide by 5 to give an average of 71 in each exam

now multiply 71*0.666666(which is 2/3)

to give 47

76-47= 29

divide by 0.33 to get 87 which is ur answer

10% of 60 is 6

1080/6 is 180 months or 15 years to recover costs( i think)

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A few days ago
sfroggy5
1) 86
1

A few days ago
Anonymous
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A few days ago
cherry
??????????????????????????? OM GOSH IM REALLY BAD AT MATH SORRY
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