a researcher measures the time (in seconds) it takes a sample of five participants to complete a memory task. It took four of the participants 4, 5, 5, and 6 seconds. If m=6, then what must be the fifth time recorded?

10 seconds

Explanation:

m here means mean.

Mean or more accurately arithmetic mean, is calculated by adding all the terms and then dividing by the number of terms.

If there are 5 terms being 4, 5, 5, 6 and a fifth one which is x, and the mean is 6. The relevant expression is:

(4 + 5 + 5 + 6 + x) / 5 = 6

Solving it:

4 + 5 + 5 + 6 + x = 6 * 5

20 + x = 30

x = 30 - 20

x = 10 seconds