Solve : 20 = 8 + x/3
Solve : 5/8y + 7 = 3/4y - 3

20 = 8 + 36/3

Step-by-step explanation:

That's the answer for the first one

a) We can be 95% sure that true average age (in weeks) at which babies begin to crawl is between 30.65 weeks and 32.89 weeks.

b) Margin of error for the confidence interval is 1.12 weeks.

Step-by-step explanation:

Let m be the estimate of the average age (in weeks) at which babies begin to crawl

Let ME be the margin of error.

then the difference between the upper bound and the lower bound gives:

m+ME - (m-ME) = 2ME = 32.89-30.65=2.24 which gives

ME=1.12 weeks