Bunuel wrote:

If the average (arithmetic mean) score for a certain student in Ms Sweeney's class is 74 on his first 6 tests then how many points must that student score on this next test to bring his overall average to 78?

A. 102

B. 84

C. 78

D. 76

E. 74

Old-fashioned but quick, see diagram below ...

A*n=S1. Find the total current point score

total (sum) by multiplying his current average (74, given) by the 6 tests he has taken:

74 * 6 = 4442. To find what score he needs to boost his overall average, first find needed overall points (second sum):

a. find what

would be the

overall new number of tests:

6 + 1 = 7 b. take the hoped-for average (78, given), multiply by overall number of tests:

78 * 7 = 5463. Then, to find the value for the score he needs, simply subtract old total from needed total:

546-444 =

Attachment:

TEST SCORE AVE FROM 74 TO 78.jpg [ 33.52 KiB | Viewed 594 times ]
Edited to replace lost text. Why does this interface sometimes eat parts of my posts?
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