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Answer 1 · 2017-07-20T13:22:58

New mean $= 94.3$ $= 94.3$

The formula to calculate mean is:

$Mean = \frac{Total of values}{number of values} M = \frac{T}{N}$ $"Mean" = "Total of values"/"number of values" " "M = T/N$

This means we also have the formulae

$T = M \times N and N = \frac{T}{M}$ $T = MxxN and N = T/M$

If the mean of 6 tests was $95$ $95$ , then the total was:

$T = 90 \times 6 = 570$ $T=90xx6 = 570$

If the student writes another test, the total will increase and the number of tests increases.

New total $= 570 + 90 = 660$ $= 570+90 =660$

New number $= 6 + 1 = 7$ $= 6+1 = 7$

We expect the new mean to be lower, because the last test score was less than the average for the first $6$ $6$ .

$M e a n = \frac{660}{7} = 94.2857$ $Mean = 660/7 =94.2857$

$M e a n = 94.3$ $Mean = 94.3$