Answer:
5/6
Step-by-step explanation:
When dividing fractions, we use a rule where we keep the first number, change the sign, and flip the second number.
3 1/3 must be converted to an improper fraction before we can do this, though.
3 1/3 is 10/3 because we multiply 3 by the denominator, also 3, and then add one, so 10/3.
Now we can divide. Remember 4 is the same thing as 4/1
10/3 ÷ 4/1
Keep the first fraction the same, change the division sign into a multiplication sign, and divide by flip the second fraction.
It ends up looking like 10/3 x 1/4
Multiply: 10 x 1 and 3 x 4
It's 10/12, but we can simplify that by dividing both the top and the bottom by 2.
The final answer is 5/6
a) 
because it is equal to the area of the shaded region between X=4 and X=6, and the probability that X falls within some interval is given by the area under the PDF.
b) 
because the shaded region is a rectangle of height 1/5 (by virtue of X following a uniform distribution over the interval [2, 7], which has length 5).
