algebra

posted by .

A parent raises a child's allowance by 12% each year. If the allowance is \$3.50 now, when will it reach \$18?

• algebra -

18 = 3.5(1.12)^n
5.142857 = 1.12^n
take log of both sides and use log rules....

n = log 5.142857/log 1.12 = 14.45

so after 14 years the allowance will be below \$18
but after 15 years it will be over \$18

Similar Questions

Mario got his \$10.00 weekly allowance on Monday. He spent 25% of his weekly allowance on Tuesday, 15% of his weekly allowance on Wednesday, and 10% more on Thursday. How much money did he have left to spend for the rest of the week?
2. math

Mario got his \$10.00 weekly allowance on Monday. He spent 25% of his weekly allowance on Tuesday, 15% of his weekly allowance on Wednesday, and 10% more on Thursday. How much money did he have left to spend for the rest of the week?
3. math

mario got his \$10.00 weekly allowance on monday. he spent 25% of his weekly allowance on tuesday, 15%of his weekly allowance on ednesday, and 10% more on thursday. how much money did he have left to spen for the rest of the week?
4. Math

Kate saves 1/5 of her allowance and spends 2/3 of her allowance at the mall. what fraction of her allowance remains?
5. math

Chelsie saves 1/5 of her allowance and spends 2/3 of her allowance at the mall. What fraction of her allowance remains?
6. algebra

Chellise saves one fifth of her allowance and spends two thirds of her allowance at the mall. What fraction of her allowance remains?
7. math

each week kelly saves 1/2 of her allowance she spends 1/3 of her allowance and 1/6 on games and movies. what does kelly do with the largest part of her allowance
8. Math

Can you check my work? If Angelona's weekly allowance is d dollars, which Expression represents her allowance, in Dollars, for x weeks?
9. Mathematoics

last week rowena spent 1/3 of her weekly allowance on snacks, 2/5 on school materials and 1/4 of the remainder, on transportation. if she save the rest of her allowance , what fraction of her allowance did she save?
10. Sewing and Technology

Which of the following represents the correct formula for calculating the amount of fabric needed to make a curtain?

More Similar Questions