Question

A daycare made $40 during their first month in business. They doubled the amount of money they earned each month. What is the total amount of money they earned after a year? $4096 $81,900 $163,800 $81,920

please give answer and way you found it im trying to learn but the way my teacher explained it doesn't make sense

Answer 1

$81,920

Explanation:

money made by january: $40

double that

money made by february: $80

double that

money made by march: $160

double that

money made by april: $320

double that

money made by may: $640

double that

money made by june: $1,280

double that

money made by july: $2,560

double that

money made by august: $5,120

double that

money made by september: $10,240

double that

money made by october: $20,480

double that

money made by november: $40,960

double that

money made by december: $81,920

the total money they made by the end of the year (december) was $81,920

Answer 2

$163,800

Explanation:

40, 80, 160, 320...

It's a geometric progression

With first term = 40

Common ratio = 80/40 = 2

After 1 year is 12 months

Find S12.

S12 = 40(2¹² - 1)/(2 -1)

= 163800