Step 1 :First, we need to calculate the population proportion (p). This can be done by dividing the number of accounts belonging to people younger than 40 (4675) by the total number of accounts (13500).
Step 2 :Next, we calculate the mean of the sampling distribution (μp), which is equal to the population proportion (p).
Step 3 :Finally, we calculate the standard deviation of the sampling distribution (σp) using the formula \(\sqrt{p(1-p)/n}\), where n is the sample size (400).
Step 4 :Let's calculate these values.
Step 5 :The population proportion (p) is \( \frac{4675}{13500} = 0.346 \).
Step 6 :The mean of the sampling distribution (μp) is equal to the population proportion (p), so \( \mu_{p} = 0.346 \).
Step 7 :The standard deviation of the sampling distribution (σp) is calculated as \( \sqrt{\frac{0.346(1-0.346)}{400}} = 0.024 \).
Step 8 :So, the final answer is: \(\boxed{p=0.346}\), \(\boxed{\mu_{p}=0.346}\), \(\boxed{\sigma_{p}=0.024}\).