Elementary Teacher

Question

How can I ask this question another way? And What type of problem is this called? Also, what is the answer?

Someday Scott is going to be a great basketball player. On Saturday, he made 20 baskets. Each day he makes 10 more baskets than the day before. On which day did he make 100 baskets?

Answer 1

20+30+40 = 90

20+30+40+50 = 140 baskets

day 1: 20

day 2: 30+20 = 50

day 3: 50+40 = 90

on day 4 he makes 90+50 = 140

he reached 100 on day 4, only 90 on day 3.

Sum of an arithmetic sequence = (n/2)(a + L) where L = the largest, a the smallest

S = (n/2)(20+50) = (n/2)(70)= (4/2)(70) = 140 on day 4

(3/2)(20+40) = (3/2)(60) = 90 on day 3

n =