Zxrxh
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CAN SOMEONE PLEASE HELP ME WITH THIS QUESTION:

Pete records all his maths test scores.
Each score is a mark out of 100.

After 9 tests his mean score is 59
After 10 tests his mean score is 58.5
After 11 tests his mean score is 60

Work out the difference between his scores on the 10th and 11th tests.
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Funksy64
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(Original post by Zxrxh)
CAN SOMEONE PLEASE HELP ME WITH THIS QUESTION:

Pete records all his maths test scores.
Each score is a mark out of 100.

After 9 tests his mean score is 59
After 10 tests his mean score is 58.5
After 11 tests his mean score is 60

Work out the difference between his scores on the 10th and 11th tests.
Total score after 9 tests = 9 X 59 = 531
Total score after 10 tests = 10 X 58.5 = 585
therefore, the score for the 10th test is 585 - 531 = 54 (because total mean goes up by 54)
After 11 tests total = 60 X 11 = 660
Score on 11th test is (total after 11th test - total after 10th test) = 660 - 585 = 75
So, the difference between the 10th and 11th test is 75 - 54 = 21
(i think this is correct, hope this helps! )
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Zxrxh
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(Original post by Funksy64)
Total score after 9 tests = 9 X 59 = 531
Total score after 10 tests = 10 X 58.5 = 585
therefore, the score for the 10th test is 585 - 531 = 54 (because total mean goes up by 54)
After 11 tests total = 60 X 11 = 660
Score on 11th test is (total after 11th test - total after 10th test) = 660 - 585 = 75
So, the difference between the 10th and 11th test is 75 - 54 = 21
(i think this is correct, hope this helps! )
you explained this so much easier thank you
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Funksy64
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(Original post by Zxrxh)
you explained this so much easier thank you
No problem!
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CraigBackner
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(Original post by Funksy64)
Total score after 9 tests = 9 X 59 = 531
Total score after 10 tests = 10 X 58.5 = 585
therefore, the score for the 10th test is 585 - 531 = 54 (because total mean goes up by 54)
After 11 tests total = 60 X 11 = 660
Score on 11th test is (total after 11th test - total after 10th test) = 660 - 585 = 75
So, the difference between the 10th and 11th test is 75 - 54 = 21
(i think this is correct, hope this helps! )
how/ why is the score for the 10th test 54?
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_gcx
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(Original post by CraigBackner)
how/ why is the score for the 10th test 54?
(10*58.5)-(9*59)=54 (ie. the difference between the total scores is 54, hence he achieved 54 in the 10th test).
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