Question

marias first four test scores are 80, 92, 88, and 86.
if maria scores an 79 on her 5th test, what is the effect on the mean?
the mean increases to 87
the mean stays the same at 86
the mean decreases to 85
the mean decreases to 84

Explanation:

Step1: Calculate initial mean

Sum of first 4 scores: $80 + 92 + 88 + 86 = 346$. Mean: $\frac{346}{4} = 86$.

Step2: Calculate new mean with 5th score

Sum with 79: $346 + 79 = 425$. New mean: $\frac{425}{5} = 85$.

Step3: Compare means

Initial mean 86 vs new mean 85: mean decreases to 85.

Answer:

C. The mean decreases to 85