Simon’s mother gave him three $5 notes on week 1. On week 2, she gave him five $5 notes. From week 3 onward, she would give him two $5 notes more than the previous week. (a) On which week would Simon receive forty-one piece of $5 notes? (b) How much money will he have at the end of 50 weeks?

(a)
(week number) x 2 + 1 = 41
(41 – 1)/2 = 20

(b)

50 x 2 = 1 = 101
(50/2) x (3 + 101) = 2600

2600 x 5 = 13000 

Ans : (a) week 20; (b) $13000.

a)

Let n be the number of weeks.

The no. of notes at nth week = 3 + (n-1)*2

Therefore 41 = 3 + (n-1)*2

38 = (n-1)*2

n = 18…sorry 20…alfie is right

He will get 41 notes at the 20th week.

b)

50th week he will get 3 + (50-1)*2 = 101 notes

1st week + 50th week = 3 + 101 = 104 notes

2nd wk + 49th wk = 5 + 99 = 104 notes

….25th + 26th wk = 104 notes 

So total notes = 25*104= 2600

TOTAL Amt = 2600*5 = 13000

Paiseh wrong again…long time no touch