Measures of the Center of the Data · Try It 5

A researcher conducted a study on the effect that playing video games has on memory recall. As part of the study, they compiled the following data:

$$\begin{array}{cc}\text{Hours Teenagers Spend on Video Games}& \text{Number of Teenagers}\\ \text{0–3.5}& \text{3}\\ \text{3.5–7.5}& \text{7}\\ \text{7.5–11.5}& \text{12}\\ \text{11.5–15.5}& \text{7}\\ \text{15.5–19.5}& \text{9}\end{array}$$
What is the best estimate for the mean number of hours spent playing video games?

Its source prints no answer for this problem, so there's nothing to check against.

OpenStax, Introductory Statistics 2e · §2.5 Measures of the Center of the Data · Try It 5