Answer:
Between 21 years and 75 years
Step-by-step explanation:
Given that a real estate company is interested in the ages of home buyers. They examined the ages of thousands of home buyers and found that the mean age was 48 years old, with a standard deviation of 9 years.
X the ages of home buyers is N(48, 9)
a) 
Hence using Cheby chev inequality

b) 

c) Using normal distribution we have

d) z value is 2.97
Hence x lies between

Between 21 years and 75 years
Answer:

Step-by-step explanation:
there are a total of 20 marbles and the chance that it is blue is 8/20 so multy that by itself and the answer is 4/25
Step-by-step explanation:
If we let the width be w, then the length is w+3.5.
This means that w(w+3.5)=11
w^2 + 3.5w - 11 = 0
2w^2 + 7w - 22 = 0 (multiply both sides by 2)
(2w+11)(w-2)=0
w = -11/2 or w = 2 (disregard w = -11/2 as distance is positive)
This means that w=2, and thus the length is 2+3.5=5.5