Answer: 0.0775
Step-by-step explanation:
Given : Mean : 
Standard deviation : 
Sample size : 
Since its normal distribution , then the formula to calculate the z-score is given by :-

For x= 28.2 hours

For x= 30 hours

The P- value = 

Hence, the probabiliy that the average time spent stydying for the sampe was between 28.2 and 30 hours = 0.0775
For the first one, I will solve for t.
s + 2t = 6, first we isolate the t variable,
2t = -s + 6, divide both sides by 2,
t = -s/2 + 3, < There's your answer for 1!
Here's the second one,
3s - 2t = 2, subtract 3s from both sides,
-2t = 2 - 3s, divide both sides by -2,
t = -1 + 3s/2 < There's your second answer!
I got -28.08695652. It doesn't repeat nor does it terminate
Distribute the 3.
3*x + 3*4
3x + 12
Hope this helps :)
Speed=distance/time
distance=205.296
time=3.12
speed=205.296/3.12=65.8
answer is 65.8 miles per hour