Asurvey was conducted that asked 1003 people how many books they had read in the past year. results indicated that x overbar equals 12.8 books and sequels 16.6 books. construct a 99% confidence interval for the mean number of books people read. interpret the interval.

The 99% confidence interval would be given (11.448;14.152).

Step-by-step explanation:

1) Important concepts and notation

A confidence interval for a mean "gives us a range of plausible values for the population mean. If a confidence interval does not include a particular value, we can say that it is not likely that the particular value is the true population mean"

represent the sample deviation

represent the sample mean

n =1003 is the sample size selected

Confidence =99% or 0.99

represent the significance level.

2) Solution to the problem

The confidence interval for the mean would be given by this formula

We can use a z quantile instead of t since the sample size is large enough.

For the 99% confidence interval the value of and , with that value we can find the quantile required for the interval in the normal standard distribution.

And replacing into the confidence interval formula we got:

And the 99% confidence interval would be given (11.448;14.152).

We are confident that about 11 to 14 are the number of books that the people had read on the last year on average, at 1% of significance.

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional

a

step-by-step explanation:

u take $30 minus $24. the answer/original($30)