15. Each ? below represents a factor between 1 and 9. Draw lines to match each fact on the left with a pattern for its products on the right.

? XO

O in the ones place

? X1

O or 5 in the ones place

? x 2

0,2,4,6, or 8 in the ones place

? X 5

The other factor in the ones place

? X9

1 less than the unknown factor in the tens place

a is the right answer

$119.20

step-by-step explanation:

$372.50 - 60% off is $149. $149-20% off is $119.20

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