Question

A video game designer is evaluating a new release and issues a pre-release version to a set of testers. The testers spend an average of 12 minutes to complete the first level, with a standard deviation of 3.5 minutes. Assuming a normal distribution for the data, 84% of players should complete the first level in less than how many minutes?

Answer 1

We call the minutes when most players complete the first level as X, as shown in the graph below

We are going to use the formula
`Z= (X-µ)/(standard deviation)` to work out the value of X

We first need the value of Z. The probability given is 84% = 0.84
Reading on the z-table, the value of Z when probability 0.84 is 1

Then substituting into the formula of Z

`1 = (X-12)/(3.5)`
1×3.5 = X - 12
X = 15.5

Answer is 15.5 minutes