Question

Suppose x has a distribution with a mean of 70 and a standard deviation of 51. Random samples of size n = 36 are drawn.

(a) Describe the  distribution.

has a binomial distribution.

has an approximately normal distribution.  

  has a geometric distribution.

has a normal distribution.

has an unknown distribution.

has a Poisson distribution.

(b) Compute the mean and standard deviation of the distribution. (For each answer, enter a number.)

=

=

What price do farmers get for their watermelon crops? In the third week of July, a random sample of 41 farming regions gave a sample mean of  = $6.88 per 100 pounds of watermelon. Assume that σ is known to be $1.90 per 100 pounds.

(a) Find the sample size necessary for a 90% confidence level with maximal error of estimate E = 0.25 for the mean price per 100 pounds of watermelon. (Enter a number. Round up to the nearest whole number.)

__ farming regions

Answer 1

According to central theorem, the distribution will be approximately normal when the sample size is large (That is n>30).

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Refer Standard normal table/Z-table or use excel function "=NORM.S.INV((1-0.05))" to find the Z-value.

Round the value to the nearest whole number.