28. baby talk: in a sample of 77 children, the mean age at which they
first began to combine words was 16.51 months, with a standard
deviation of 9.59 months.
a. construct a 95% confidence interval for the mean age at which
children first begin to combine words.
b. if a sample of 50 children had been studied, would you expect
the confidence interval to be wider or narrower than the interval
constructed in part (a)? explain.

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!