An advertising agency conducted a survey and found that the number of units sold, N, is related to the amount a spent on advertising (in dollars) by the following formula: N = 4,500 + 200 ln a (a ¡Ý 1)How many units are sold after spending $1,000?

just plug in a=1000:

N = 4500 + 200 ln 1000
= 4500 + 200*6.9077
= 5881