A certain psychological test measures empathy and emotional intelligence. The score, S, of a randomly selected senior student at a large university has a mean of 123 and a standard deviation of 29. The score, F, of a randomly selected first-year student at a large university has a mean of 104 and a standard deviation of 34. Suppose we randomly select one senior student and one first-year student. We can consider S and F to be independent random variables.

Calculate the standard deviation of the difference D = S – F.

σD = 17.7482
σD = 19
σD = 44.6878
σD = 227

- "runner b is moving at a slower rate."

- "the graphs shown are graphs of distance(km) against time(min).

the slopes of this graphs are are given by:

slope = (change in y)/(change in x)

= (change in distance)/(change in time)

this is the formula for finding the speed. so, the slope of these graphs represent the speed of the runner.

taking each division in the graph to represent 1 on both axis:

runner a ⇒ speed = (2-0)/(1-0)

= 2/1

= 2 km/min

runner b ⇒ speed = (3-0)/(3-0)

= 3/3

= 1 km/min

this shows that   runner b is moving at a slower rate."

1. 2

2. 11

3. 5

4. 6

5. 7

6. 5

7. -1

8. 1

step-by-step explanation: