OBJECTIVE FORESTRY

FORESTRY

AGRICULTURAL STATISTICS AND ECONOMICS

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
In a crash test of 15 troopers, collision repair costs are found to have a distribution that is approximately normal, with a mean of $1800 and a standard deviation of $950. Construct a 99% confidence interval for the repair cost.
A
(1070, 2530)
B
(1273, 2326)
C
(1799, 1801)
D
None of these.
Explanation: 

Detailed explanation-1: -Since 95% of values fall within two standard deviations of the mean according to the 68-95-99.7 Rule, simply add and subtract two standard deviations from the mean in order to obtain the 95% confidence interval.

Detailed explanation-2: -Calculating a C% confidence interval with the Normal approximation. ˆp±z√ˆp(1−ˆp)n, where the value of z is appropriate for the confidence level. For a 95% confidence interval, we use z=1.96, while for a 90% confidence interval, for example, we use z=1.64.

Detailed explanation-3: -With a 95 percent confidence interval, you have a 5 percent chance of being wrong. With a 90 percent confidence interval, you have a 10 percent chance of being wrong. A 99 percent confidence interval would be wider than a 95 percent confidence interval (for example, plus or minus 4.5 percent instead of 3.5 percent).

There is 1 question to complete.