He could buy 6 combinations of stickers
A 99% confidence interval will be wider compared to a 95% confidence interval. This is because while you don't know what the true value of mu is, you are more confident that the parameter is in the interval.
In essence, you are casting a wider net which leads to the higher level of confidence. Imagine if there was a 100 mile stretch of straight land, and somewhere on this line was a special rock that you are looking for. You would be 100% confident if you said "the rock is somewhere on that piece of land", and less confident the more you shrunk the interval.
Answer:
128 cm^2
Step-by-step explanation:
The area of a trapezoid is given by
A = 1/2 (b1+b2) h
where b1 and b2 are the lengths of the bases and h is the height
A =1/2( 10+22) * 8
A = 1/2 (32)8
= 128
As we have to solve for b, it means we have to isolate b
So first of all subtract 
from both sides
So we get
Now we need b , but its b^2 , so we can take square root on both sides.
taking square roots on both sides
Hence option B is correct
