The answer to this would be 11.82
Rational numbers are numbers which can be written as a fraction (the formula is p/q). They don't include roots we can't solve in order to get a whole number and pi.
A. 776, pi, 25.209, √9 ---> NO (because of pi)
B. 726, 7/34, 20.209, √9 ---> YES
C. √3, 7/39, 20.3, √9 ---> NO (because of √3)
D. 726, 7/34, 20.209, √5 ---> NO (because of √5
Note that √9 = 3, so it IS a rational number.
Q18)
7/0.75 = 28/3
28/3(45) = 420 -> 420/60 = 7
Therefore the answer is B. 7 minutes.
Q20)
60.90/5 = 12.18
12.18(7) = 85.26
85.26+14.99 = 100.25
Therefore the answer is D. $100.25.
You normally use division what u do is u did if 24.99 by 2
199.
the z score for the 90th percentile is 1.28, so you can solve the equation

which gets you the 199