In mathematics, a rational number is a number such as −3/7 that can be expressed as the quotient or fraction p/q of two integers, a numerator p and a non-zero denominator q
Answer:
Step-by-step explanation:
Given that the random variable X is normally distributed, with
mean = 50 and standard deviation = 7.
Then we have z= 
Using this and normal table we find that
a) 
b) When z=0.02
we get

c) 90th percentile z value =1.645
90th percentile of X 