Answer:
We conclude that the mean is greater than 25.
Step-by-step explanation:
We are given the following in the question:
Population mean, μ = 25
Sample mean,
= 27
Sample size, n = 100
Alpha, α = 0.05
Sample standard deviation, s = 6.5
First, we design the null and the alternate hypothesis

We use One-tailed(right) z test to perform this hypothesis.
Formula:

Putting all the values, we have

Now, 
Since,

We reject the null hypothesis and accept the alternate hypothesis.
Thus, the mean is greater than 25.
He would pay $2119.72 and his remaing balance would be $243,780.28
Answer:
D.5
Step-by-step explanation:
You can write the following equations from the information given:
y=x+3 (1)
11x+5y=47 (2)
x is the number of hardback books
y is the number of paperback books
You can replace (1) in (2):
11x+5(x+3)=47
11x+5x+15=47
16x=47-15
16x=32
x=32/16
x=2
Then, you can replace the value of x in (1) to find the value of y:
y=2+3
y=5
According to this, the answer is that Jamal bought 5 paperback books.