Answer:
15) a) 8
b) y + 2
c) y - 1
16) True
17) 2n - 1, where n is an integer
18) a) 3p + 4q
b) 500 - 3p - 4q
Answer:
The required confidence inteval = 94.9%.
Step-by-step explanation:
Confidence interval: Mean ± Margin of error
Given: A confidence interval for the true mean diameter of all oak trees in the neighbourhood is calculated to be (36.191, 42.969).
i.e. Mean + Margin of error = 42.969 (i)
Mean - Margin of error = 36.191 (ii)
Adding (i) and (ii), we get

Margin of error = 42.969-39.58 [from (i)]
= 3.389
Margin of error = 
here n= 25 
i.e.

Using excel function 1-TDIST.2T(2.054,24)
The required confidence inteval = 94.9%.
43 < y - 30
add 30 to both sides
73 < y
y can be anything that is greater than 73
so it could be...
101, 74, 90, 75, 980767, 5674, etc.
Hope this helps!
Thirty four times 000 which I am assuming is just zeroes would be 0.