The number of members on an organization increases by an average of 125 members annually. There were 3,875 members in 1971. Choose the equation below that gives the approximate number of members, Mn, in the nth year after 1970.

A.

Mn = Mn-1 + 125 for n > 1; M1 = 3,750

B.

Mn = Mn-1 + 125 for n > 1; M1 = 3,875

C.

Mn-1 = Mn + 125 for n > 1; M1 = 3,875

D.

Mn-1 = Mn + 125 for n > 1; M1 = 3,750

B.

Mn = Mn-1 + 125 for n > 1; M1 = 3,875

Step-by-step explanation:

Since they tell us after 1970, the first data would be that of 1971 and also that if we started since 1970, we do not know the data of 1969, therefore answer B is correct.

Replacing:

Let M1 = 1971 then Mn-1, that is M0 = 1970, we know that the population of 1970 the population is 3750, because it would be 125 less than the subsequent year, and in 1975 there are 3875. Therefore:

in n = 1

M1 = M0 + 125

3875 = 3750 + 125

this gives an equality, thus fulfilling the equation.