Find the value of n in each of the following proportions. 1. 18/n = 21/28

2. 12/16 = n/64

24

Step-by-step explanation:

18/n = 21/28                    You can cancel, but calculators make that unnecessary.   Cross multiply

21n = 18 * 28

21n = 504                         Divide by 21

n = 504 / 21

n = 24

12/16 = n / 64                    Cross Multiply

16n = 12 * 64

16n = 768                         Divide by 16

n = 768/16

n = 48

step-by-step explanation:

part a. the differences are decreasing, so we know the sequence is not arithmetic. the ratios are constant (=3/4), so we know the sequence is geometric.

part b. from part a, we know the common ratio is 3/4, so each term is 3/4 of the one before. the initial term is the number of gallons at h=1.

g[h] = (3/4)·g[h-1]

g[1] = 384 . . . . initial value required for a recursive definition

part c. the general formula for a geometric sequence is

a[n] = a[1]·r^(n-1)

we have a[1] = 384, r = 3/4, and the term number given by h. the formula that follows is

g[h] = 384·(3/4)^(h-1)

part d. filling in the value and doing the arithmetic, we have

g[12] = 384·(3/4)^11 ≈ 384·0.042235136 ≈ 16.2183 . . gallons

part e. each gallon is 4 quarts, so

16.2183 gal × 4 qt/gal = 64.8732 qt