First, it is important to know that speed is equal to distance divided by time. I took a picture of my work. Let me know if you still have questions or cannot read something I've written. Thank you!
The most Kilometers traveled per one hour was traveled by THE BOAT at 75 Km/h. Therefore, the boat had the fastestaverage speed.
Let X be the national sat score. X follows normal distribution with mean μ =1028, standard deviation σ = 92
The 90th percentile score is nothing but the x value for which area below x is 90%.
To find 90th percentile we will find find z score such that probability below z is 0.9
P(Z <z) = 0.9
Using excel function to find z score corresponding to probability 0.9 is
z = NORM.S.INV(0.9) = 1.28
z =1.28
Now convert z score into x value using the formula
x = z *σ + μ
x = 1.28 * 92 + 1028
x = 1145.76
The 90th percentile score value is 1145.76
The probability that randomly selected score exceeds 1200 is
P(X > 1200)
Z score corresponding to x=1200 is
z = 
z = 
z = 1.8695 ~ 1.87
P(Z > 1.87 ) = 1 - P(Z < 1.87)
Using z-score table to find probability z < 1.87
P(Z < 1.87) = 0.9693
P(Z > 1.87) = 1 - 0.9693
P(Z > 1.87) = 0.0307
The probability that a randomly selected score exceeds 1200 is 0.0307
Y - x = 6
y + 2x = 57
2y - 2x =12
y + 2x = 57
∴3y = 69
y = 23
23 - x = 6
-x = -17
x =17
large van = 23
small van = 17
