A parachute company sells safety devices that are designed to fire, releasing the reserve parachute, at a mean height of 304.8 m with a standard deviation of 11.8 m. The company recently updated the devices, which, the lead engineer suspects, has caused the standard deviation, , to decrease. He measures the heights at which the devices fire for a random sample of 12 of the updated devices. The heights at which the devices fire have a sample standard deviation of 7.5 m. Assume the heights at which the updated devices fire follow a normal distribution. Can the engineer conclude that the population standard deviation, G, is less than 11.8 m? To answer, complete the parts below to perform a hypothesis test. Use the 0.05 level of significance. (a) State the null hypothesis H and the alternative hypothesis H, that you would use for the test. HO H₁:0 . O (b) Perform a chi-square test and find the p-value. Here is some information to help you with your chi-square test. Chi-square Distribution Step 1: Enter the number of degrees of freedom. Step 3: Enter the test statistic (Round to 3 decimal places) 00 00 00 Step 4: Shade the area represented by the p-value. S 020 0-0 0-0 The value of the test statistic is given by 7 =- (x-1)=² The p-value is the area under the curve to the left of the value of the test statistic. Step 2: Select one-tailed or two-tailed. O One-tailed OTwo-tailed Step 5: Enter the p-value (Round to 3 decimal places) 5 0.1- X S (c) Based on your answer to part (b), choose what can be concluded, at the 0.05 level of significance, about the population standard deviation in the heights at which the updated devices fire. O Since the p-value is less than (or equal to) the level of significance, the null hypothesis is rejected. So, there is enough evidence to conclude that the standard deviation is less than 11.8 m O Since the p-value is less than (or equal to) the level of significance, the null hypothesis is not rejected. So, there is not enough evidence to conclude that the standard deviation is less than 11.8 m O Since the p-value is greater than the level of significance, the null hypothesis is rejected. So, there is enough evidence to conclude that the standard deviation is less than 11.8 m O Since the p-value is greater than the level of significance, the null hypothesis is not rejected. So, there is not enough evidence to conclude that the standard deviation is less tha 118 m x S

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A parachute company sells safety devices that are designed to fire, releasing the reserve parachute, at a mean height of 304.8 m with a standard deviation of
11.8 m. The company recently updated the devices, which, the lead engineer suspects, has caused the standard deviation, , to decrease. He measures the
heights at which the devices fire for a random sample of 12 of the updated devices. The heights at which the devices fire have a sample standard deviation of
7.5 m. Assume the heights at which the updated devices fire follow a normal distribution.
Can the engineer conclude that the population standard deviation, O, is less than 11.8 m? To answer, complete the parts below to perform a hypothesis test. Use
the 0.05 level of significance.
(a) State the null hypothesis H and the alternative hypothesis H, that you would use for the test.
W
•
(b) Perform a chi-square test and find the p-value.
Here is some information to help you with your chi-square test.
(n-1)3²
0
020
The value of the test statistic is given by
Chi-square Distribution
Step 1: Enter the number of degrees
of freedom.
Step 3: Enter the test statistic.
(Round to 3 decimal places.)
The p-value is the area under the curve to the left of the value of the test statistic.
Step 2: Select one-tailed or two-tailed
O One-tailed
OTwo-tailed
Step 4: Shade the area represented
by the p-value.
S
Step 5: Enter the p-value.
(Round to 3 decimal places)
S
03-
(c) Based on your answer to part (b), choose what can be concluded, at the 0.05 level of significance, about the population standard deviation in the
heights at which the updated devices fire.
O Since the p-value is less than (or equal to) the level of significance, the mull hypothesis is rejected. So, there is enough
evidence to conclude that the standard deviation is less than 11.8 m.
O Since the p-value is less than (or equal to) the level of significance, the null hypothesis is not rejected. So, there is not
enough evidence to conclude that the standard deviation is less than 118 m.
O Since the p-value is greater than the level of significance, the null hypothesis is rejected. So, there is enough evidence
to conclude that the standard deviation is less than 11.8 m.
O Since the p-value is greater than the level of significance, the null hypothesis is not rejected. So, there is not enough
evidence to conclude that the standard deviation is less than 11.8 m.
X
85
Transcribed Image Text:A parachute company sells safety devices that are designed to fire, releasing the reserve parachute, at a mean height of 304.8 m with a standard deviation of 11.8 m. The company recently updated the devices, which, the lead engineer suspects, has caused the standard deviation, , to decrease. He measures the heights at which the devices fire for a random sample of 12 of the updated devices. The heights at which the devices fire have a sample standard deviation of 7.5 m. Assume the heights at which the updated devices fire follow a normal distribution. Can the engineer conclude that the population standard deviation, O, is less than 11.8 m? To answer, complete the parts below to perform a hypothesis test. Use the 0.05 level of significance. (a) State the null hypothesis H and the alternative hypothesis H, that you would use for the test. W • (b) Perform a chi-square test and find the p-value. Here is some information to help you with your chi-square test. (n-1)3² 0 020 The value of the test statistic is given by Chi-square Distribution Step 1: Enter the number of degrees of freedom. Step 3: Enter the test statistic. (Round to 3 decimal places.) The p-value is the area under the curve to the left of the value of the test statistic. Step 2: Select one-tailed or two-tailed O One-tailed OTwo-tailed Step 4: Shade the area represented by the p-value. S Step 5: Enter the p-value. (Round to 3 decimal places) S 03- (c) Based on your answer to part (b), choose what can be concluded, at the 0.05 level of significance, about the population standard deviation in the heights at which the updated devices fire. O Since the p-value is less than (or equal to) the level of significance, the mull hypothesis is rejected. So, there is enough evidence to conclude that the standard deviation is less than 11.8 m. O Since the p-value is less than (or equal to) the level of significance, the null hypothesis is not rejected. So, there is not enough evidence to conclude that the standard deviation is less than 118 m. O Since the p-value is greater than the level of significance, the null hypothesis is rejected. So, there is enough evidence to conclude that the standard deviation is less than 11.8 m. O Since the p-value is greater than the level of significance, the null hypothesis is not rejected. So, there is not enough evidence to conclude that the standard deviation is less than 11.8 m. X 85
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