Answer: 
Step-by-step explanation:
Sampling distribution of the sample proportion
:

The sampling distribution of the sample proportion
has mean =
and standard deviation =
.
Given : The proportion of left handed people in the population is about 0.10.
i.e. p=0.10
sample size : n= 300
Then , the sampling distribution of the sample proportion
will be :-


(approx)
Hence, the sampling distribution of the sample proportion
is 
Answer: d = 12
Step-by-step explanation: First isolate d/3 by subtracting 10 from both sides of the equation. That gives you d/3 = 4.
From here, since <em>d</em> is being divided by 5, multiply both sides of the equation by 5 so <em>d = 12</em>.