Automobile license plates in Massachusetts usually consist of three digits followed by three letters. The first digit is never zero. How many different plates of this type could be made ?

1,58,18,400

Step-by-step explanation:

1st digit can have the values 1-9 (9 distinct values)

2nd digit can have the values 0-9 (10 distinct values)

3rd digit can have the values 0-9 (10 distinct values)

1st letter can have the value A-Z (26 distinct values)

2nd letter can have the value A-Z (26 distinct values)

3rd letter can have the value A-Z (26 distinct values)

Total number of different plates possible = 9*10*10*26*26*26

=1,58,18,400

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