Question

QUESTION 10

Use your TI83 to find the upper end of the interval requested:

A 90% confidence interval for the average lifespan of the large tortoise if a sample of 41 such animals have an average life of 69 years with a population deviation of 24 years

round to the nearest hundredth of a year

QUESTION 11

Use your TI83 to find the upper end of the interval requested:

A 95% confidence interval for the average waiting time at the drive-thru of a fast-food restaurant if a sample of 61 customers have an average waiting time of 106 seconds with a population deviation of 22 seconds

round to the nearest hundredth of a second

QUESTION 12

Use your TI83 to find the lower end of the interval requested:

A 95% confidence interval for the average waiting time at the drive-thru of a fast-food restaurant if a sample of 77 customers have an average waiting time of 78 seconds with a population deviation of 35 seconds

round to the nearest hundredth of a second

Answer 1

Answer:

1.

Given,

sample size = 41

mean = 69

standard deviation = 24

alpha = 0.1

here for 90% confidence interval , z value is 1.645

Now consider

Interval = xbar +/- z*s/sqrt(n)

substitute values

= 69 +/- 1.645*24/sqrt(41)

= 69 +/- 6.17

= (69 - 6.17 , 69 + 6.17)

= (62.83 , 75.17)

lower end = 62.83

upper end = 75.17

2.

Given,

sample size = 61

mean = 106

standard deviation = 22

alpha = 0.05

here for 95% confidence interval , z value is 1.96

Now consider

Interval = xbar +/- z*s/sqrt(n)

substitute values

= 106 +/- 1.96*22/sqrt(61)

= 106 +/- 5.52

= (106 - 5.52 , 106 + 5.52)

= (100.48 , 111.52)

upper end = 111.52

3.

Given,

sample size = 77

mean = 78

standard deviation = 35

alpha = 0.05

here for 90% confidence interval , z value is 1.96

Now consider

Interval = xbar +/- z*s/sqrt(n)

substitute values

= 78 +/- 1.96*35/sqrt(77)

= 78 +/- 7.82

= (78 - 7.82 , 78 + 7.82)

= (70.18 , 85.82)

lower end = 70.18

I hope it works for you.