Question

In a series of tests, A appeared for 8 tests. Each test was marked out of 30 and averages 25. However, while checking his files, A could only find 7 of the 8 tests. For these, he scored 29 26, 18, 20, 27, 24 and 29. Determine how many marks he scored for the eighth test.

Answer 1

Total number of tests = 8
Average score of A = 25
Let the score of 8thth test be x
Then, the total score of 8 tests = 29 + 26 + 18 + 20 + 27 + 24 + 29 + x
Now , we have
Mean =Toatalscoreof8testsTotalnumberoftests=Toatalscoreof8testsTotalnumberoftests
⇒25=29+26+18+20+27+24+29+x8⇒25=29+26+18+20+27+24+29+x8
⇒25×8=173+x⇒25×8=173+x
⇒x+173=200⇒x+173=200
⇒x=200−173⇒x=200−173
⇒x=27⇒x=27
Thus, A scored 27 marks in the eight test.