The time (in days) until maturity of a certain variety of tomato plant is Normally distributed, with mean µμ and standard deviation σ=2.4σ=2.4 . I select a simple random sample of four plants of this variety and measure the time until maturity. The sample yields x¯=65x¯=65 . A 95% confidence interval for µμ (in days) is:

A. 65.00 ± 4.70.
B. 65.00 ± 2.35.
C. 65.00 ± 3.95.
D. 65.00 ± 1.97.

B. 65.00 ± 2.35.

Step-by-step explanation:

We have that to find our level, that is the subtraction of 1 by the confidence interval divided by 2. So:

Now, we have to find z in the Ztable as such z has a pvalue of .

So it is z with a pvalue of , so

The confidence interval has the following format:

So

So the correct answer is:

B. 65.00 ± 2.35.

$25

step-by-step explanation:

25 - 4.50 = 20.5

20.5 / 2 = 10.25

10.25 + 10 = 20.25

20.25 - 12.50 = 7.75

therefore the answer is $25 as shown as the first number.