The formula used to compute a confidence interval for the mean of a normal population when n is small is the following.

x^^\_ +/-\(t text( critical value)\)s/sqrt(n)

what is the appropriate t critical value for each of the following confidence levels and sample sizes? (round the answers to two decimal places.)

(a) 90% confidence, n = 17

(b) 90% confidence, n = 12

(c) 99% confidence, n = 24

(d) 90% confidence, n = 25

a)

b)

c)

d)

Step-by-step explanation:

We are given the following information in the question:

Confidence interval:  

We have to find the appropriate t critical values for each of the following confidence levels and sample sizes:

a) 90% confidence, n = 17

Degree of freedom = n - 1 = 16

b) 90% confidence, n = 12

Degree of freedom = n - 1 = 11

c) 99% confidence, n = 24

Degree of freedom = n - 1 = 23

d) 99% confidence, n = 25

Degree of freedom = n - 1 = 24

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step-by-step explanation:

d. $180

step-by-step explanation:

if the dimensions of the room is 9ft by 12 ft, we have the area of the floor as,

so the area of the floor is 108 square feet, converting that into square yards we get,

the cost of carpet is $15 per square yard, therefore the cost of carpet for 12 square yards is,

hence, the cost of carpet is $180.

assuming the dimensions of the room be,

15 ft by 12 ft

so, the area of the floor of that room is,

we can convert 180 square feet into square yards, we know that,

1 sq ft = 0.111 sq yard

so, 180 square feet is,

so the area of floor is 20 square yards.

now, the cost of carpet is 15 dollars per square yard, therefore the cost of carpet for 20 square yards is,

so, it will cost $300.