in short, we simply divide the whole 300 by (3+7), to get in a 3:7 ratio, and then distribute accordingly.

Part a is correct.
Part b can be done a couple ways.
1) Use binomial distribution. p = 0.2, n = 144
P(x>3) = 1 - P(x=0) -p(x=1) -p(x=2) -p(x=3)
where

2) Assume a normal distribution with mean = 28.2, stdev = 4.8

Look up z-value in normal table to find probability.
Hope that helps.
Answer:
x = 5
Step-by-step explanation:
Given that,

Cross multiplying both sides,

Taking like terms together,

So, the value of x is equal to 5.
Answer: The correct answer is the last choice.
In the first segment of the trip, the car goes from 0 to 2 hours and the line is moving up. Therefore, it traveled for 2 hours.
In the second segment, the line went straight horizontal for 1 hour. That means the distance didn't change, in other words it didn't move.
In the last segment, it moved up again for 2 hours.
This is an impossible equation. If sqrt(x) = sqrt(x), and sqrt(x) + 2 = sqrt(x) + 12, then that would mean that 2=12, which is incorrect.