A sample of 30 randomly selected oranges was taken from a large population, and their diameters were measured. The mean diameter of the sample was 91 mm and the standard deviation was 8 mm. Assuming a Normal distribution, calculate (correct to one decimal place) 85% confidence limits for the mean diameter of the whole population of oranges.

A 87.9 mm and 94.1 mm

B 89.9 mm and 93.1 mm

C 88.1 mm and 93.9 mm

D 88.9 mm and 93.1 mm

D 88.9 mm and 93.1 mm

Step-by-step explanation:

We have that to find our level, that is the subtraction of 1 by the confidence interval divided by 2. So:

Now, we have to find z in the Ztable as such z has a pvalue of .

So it is z with a pvalue of , so

Now, find M as such

In which is the standard deviation of the population and n is the size of the sample.

The lower end of the interval is the sample mean subtracted by M. So it is 91 - 2.1 = 88.9mm

The upper end of the interval is the sample mean added to M. So it is 91 + 2.1 = 93.1 mm

So the correct answer is:

D 88.9 mm and 93.1 mm

the f

last graph i believe

step-by-step explanation:

worked it out i believe

3

step-by-step explanation:

in standard form:

a= dictionaries

b= maps

you have to buy 3 dictionaries, so put a 3 next to the a (dictionaries) so that you can multiply them by each other.

a3+b= 60 (the amount of money you have)

we already know the cost of a=15 so replace a with $15

($15 x 3)+b=60

multiply 15 and 3 to get $45 and replace it with $45

45+b=60

and then replace b with 15 to get the total:

45+15=60

that means you have $15 left after buying 3 dictionaries.

15 divided by the cost of a map ($5) equals 3.

so you can buy 3 maps.

sorry if it was confusing!