\begin{tabular}{|c|c|c|c|}\hline Question 5 , & ר & HW Score: 73.89%, & \{్ర \\\hline Part 3 of 4 & & (x) Points: 0.5 of 1 & Save \\\hline\end{tabular}A simple random sample of size n=14 is obtained from a population with μ=69 and σ=16.(a) What must be true regarding the distribution of the population in order to use the normal model to compute probabilities involving the sample mean? Assuming that this condition is true, describe the sampling distribution of xˉ.(b) Assuming the normal model can be used, determine P(xˉ<73.4).(c) Assuming the normal model can be used, determine P(xˉ≥70.7).(a) What must be true regarding the distribution of the population?A. Since the sample size is large enough, the population distribution doe need to be normal.B. The sampling distribution must be assumed to be normal.C. The population must be normally distributed.D. The population must be normally distributed and the sample size must be large.Assuming the normal model can be used, describe the sampling distribution xˉ. Choose the correct answer below.
Q. \begin{tabular}{|c|c|c|c|}\hline Question 5 , & ר & HW Score: 73.89%, & \{్ర \\\hline Part 3 of 4 & & (x) Points: 0.5 of 1 & Save \\\hline\end{tabular}A simple random sample of size n=14 is obtained from a population with μ=69 and σ=16.(a) What must be true regarding the distribution of the population in order to use the normal model to compute probabilities involving the sample mean? Assuming that this condition is true, describe the sampling distribution of xˉ.(b) Assuming the normal model can be used, determine P(xˉ<73.4).(c) Assuming the normal model can be used, determine P(xˉ≥70.7).(a) What must be true regarding the distribution of the population?A. Since the sample size is large enough, the population distribution doe need to be normal.B. The sampling distribution must be assumed to be normal.C. The population must be normally distributed.D. The population must be normally distributed and the sample size must be large.Assuming the normal model can be used, describe the sampling distribution xˉ. Choose the correct answer below.
Question Prompt: Question Prompt: Determine the conditions required for using the normal model for the sample mean and calculate probabilities for given conditions using the normal distribution.
Step 1: Step 1: For the normal model to be applicable, the population from which the sample is drawn must be normally distributed. This is because the Central Limit Theorem, which allows the use of the normal model for the sample mean, requires either a normal population distribution or a sufficiently large sample size (usually n≥30) to approximate normality. Here, since n=14, which is not large, the population must be normally distributed. Correct answer: C.
Step 2: Step 2: Assuming the population is normally distributed, the sampling distribution of the sample mean xˉ will also be normally distributed. The mean of xˉ is equal to the population mean μ, and the standard deviation of xˉ (standard error) is σ/n. Calculation: σ/14=16/14≈4.28.
Step 3: Step 3: To find P(xˉ<73.4), convert xˉ to a standard normal variable Z. Calculation: Z=(xˉ−μ)/(σ/n)=(73.4−69)/4.28≈1.03. Use the Z-table to find P(Z<1.03)≈0.8485.
Step 4: Step 4: To find P(xˉ≥70.7), first calculate Z for 70.7. Calculation: Z=(70.7−69)/4.28≈0.40. Use the Z-table to find P(Z<0.40)≈0.6554. Since we need P(Z≥0.40), it is 1−0.6554=0.3446.