The life in hours of a 75-watt light bulb is known to be normally distributed with σ = 22 hours. a random sample of 20 bulbs has a mean life of x overscript bar endscripts = 1012 hours. suppose that we wanted the total width of the two-sided confidence interval on mean life to be six hours at 95% confidence. what sample size should be used? round up the answer to the nearest integer.

207

Step-by-step explanation:

Data provided in the question:

σ = 22 hours

Mean = 1012 hours

Confidence level = 95%

Width of the confidence level = 6 hours

Therefore,

Margin of error, E = ( Width of the confidence level ) ÷ 2

= 6 ÷ 2

= 3

also,

E =

here,

z value for 95% confidence level  is 1.96

Thus,

3 =

or

√n =

or

√n = 14.373

or

n = 206.59 ≈ 207

hello :

by applying the distributive property :

6 × 4.3 = 6 × ( 4 + 0.3 )

            =   (6 ×   4) + (6 ×   0.3)

            = 24 + 1.8

6 × 4.3 = 25.8

the final amount you will pay is $68.04.

the tip is determined by the pre-tax amount, so we calculate the tip based on the original bill, not after we've added sales tax.

to find the tip:

we can divide 54.00 by 100 to get 1% of 54. then we multiply that by 18.

54 / 100 = .54

.54 x 18 = 9.72

tip = 9.72$

to find the tax:

we can divide 54.00 by 100 to get 1% of 54. then we can multiply that by 8 to get 8%.

54 / 100 = .54

.54 x 8 = 4.32

tax= 4.32

now we can add the tip and tax to the bill to get our total.

54 + 9.72 + 4.32 = 68.04

total: $68.04

step-by-step explanation: