Simple Regression

Question

The question asks for the slope and intercept, but I don't have a correlation coefficient or the raw data (just sample size, mean, and standard deviation).

Answer 1

Your linear model is $Y=\beta_1 X + \beta_0 + \varepsilon$, where $Y$ is the time spent and $X=1$ if senior, $0$ otherwise.

In a simple linear model like that, we know that the least square estimates of $\beta_1$ and $\beta_0$ are given by: https://upload.wikimedia.org/math/e/5/b/e5b794026921e4b402ae7fb58b2fd7c3.png where $\bar{x}$ and $\bar{y}$ are the sample means.

With the data you have, you can calculate $Cov(X,Y)$, $V(X)$, $\bar{x}$ and $\bar{y}$. I suggest you start by $\bar{x}$ and $\bar{y}$ as you'll need them to calculate $Cov(X,Y)$.