Answer: 0.6827
Step-by-step explanation:
Given : Mean IQ score : 
Standard deviation : 
We assume that adults have IQ scores that are normally distributed .
Let x be the random variable that represents the IQ score of adults .
z-score : 
For x= 90

For x= 120

By using the standard normal distribution table , we have
The p-value : 

Hence, the probability that a randomly selected adult has an IQ between 90 and 120 =0.6827
Answer:
2/π ≈ 0.637 m/s
Step-by-step explanation:
The rate of change of area with respect to time is ...
A = πr²
dA/dt = 2πr·dr/dt
Filling in given values in the above equations, we can find r and dr/dt.
25π = πr² ⇒ r = 5
20 = 2π·5·dr/dt
dr/dt = 20/(10π) = 2/π . . . . meters per second
The radius is increasing at the rate of 2/π ≈ 0.637 meters per second.