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Hi, i really need help with these questions, I don't know how to do some of them and I don't know if I am doing the rest correctly 
. Can someone pleas review my work and point out any mistakes awell as tell me how to do the questions that I left blank? Thanks.
1. how long does it take $500 to grow to $510 at 9% simple interest?
p=irt
t=p/ir
t=500/510(0.09)
t=10.89
so it would take 10.89 years
2. a donor gave $75 000 to a town council stipulating that it was to be invested for 10years and the accumulated amount used to enlarge the public library. The money earned 8% interest and compounded semi-annually.
a) How much money was available to spend on the library?
A = P(1 + r)n
=75000(1+ 0.08)10
=161 919. 37
b) How much interest did the investment earn
How do you do this?
3. Henry plans to make an equal deposit at the end of every three months for 5 years in a trust account that pays interest at 12% per annum, compounded quarterly. If he expects to have $100 000 at the end of 5 years, what must be his quarterly deposit?
A = P(1 + r)n
A= 100 000
P=
r= 12/4, 3%
n= 5years
P=A/(1- r)n
=100 000(1- 0.03)^5
=858 73.40
4. Marisa estimates that, in three years, the cost of her first year of university will be $12 500. Marisa decides to invest some money now at 6.4% per annum, compounded monthly. How much money should she put aside now so that she has enough money?
A = P(1 + r)n
A= 12 500
P=
r= 6.4/12
n= 3
P=A/( 1 + r) n
= 12 500/(1+ 0.0053)^3
= 12302
5. Judwinder deposits $25 at the end of each month for 3 years in an account paying 8% compounded monthly.
a) Find the amount in the account at the end of 3 years
A = P(1 + r)n
= 25(1+0.0066
b) In Jugwinder makes no more deposits and no withdrawals, find the amount in the account at the end of 5 years.
6. The purchase of a new car, including taxes, is $14 387.45. What down payment will allow the balance to be paid off by monthly installments of $250 for 36 months, when interest is charged at 15% compounded monthly
7. Roxanne buys a DVD/VCR player for $50 down and ten monthly payments for $40 each. The first payment is due next mounth. The interest rate is 18% per annum, compounded monthly. What is the selling price of the player?
8. At what interest rate would a sum of money double in 7 years.
A = P(1 + r)n
10=5(1+r)7
10=5(7+7r)
10=35 + 35r
-25=35r
0.71428 x 100
71%
********
can some one tell me how to do the ones I left blank. Also, i don't understand the per annum, mounthly. Are you supposed to divide the interest rate by 12 to get the new % of interst?
Thanks,
Aka
. Can someone pleas review my work and point out any mistakes awell as tell me how to do the questions that I left blank? Thanks. 1. how long does it take $500 to grow to $510 at 9% simple interest?
p=irt
t=p/ir
t=500/510(0.09)
t=10.89
so it would take 10.89 years
2. a donor gave $75 000 to a town council stipulating that it was to be invested for 10years and the accumulated amount used to enlarge the public library. The money earned 8% interest and compounded semi-annually.
a) How much money was available to spend on the library?
A = P(1 + r)n
=75000(1+ 0.08)10
=161 919. 37
b) How much interest did the investment earn
How do you do this?
3. Henry plans to make an equal deposit at the end of every three months for 5 years in a trust account that pays interest at 12% per annum, compounded quarterly. If he expects to have $100 000 at the end of 5 years, what must be his quarterly deposit?
A = P(1 + r)n
A= 100 000
P=
r= 12/4, 3%
n= 5years
P=A/(1- r)n
=100 000(1- 0.03)^5
=858 73.40
4. Marisa estimates that, in three years, the cost of her first year of university will be $12 500. Marisa decides to invest some money now at 6.4% per annum, compounded monthly. How much money should she put aside now so that she has enough money?
A = P(1 + r)n
A= 12 500
P=
r= 6.4/12
n= 3
P=A/( 1 + r) n
= 12 500/(1+ 0.0053)^3
= 12302
5. Judwinder deposits $25 at the end of each month for 3 years in an account paying 8% compounded monthly.
a) Find the amount in the account at the end of 3 years
A = P(1 + r)n
= 25(1+0.0066
b) In Jugwinder makes no more deposits and no withdrawals, find the amount in the account at the end of 5 years.
6. The purchase of a new car, including taxes, is $14 387.45. What down payment will allow the balance to be paid off by monthly installments of $250 for 36 months, when interest is charged at 15% compounded monthly
7. Roxanne buys a DVD/VCR player for $50 down and ten monthly payments for $40 each. The first payment is due next mounth. The interest rate is 18% per annum, compounded monthly. What is the selling price of the player?
8. At what interest rate would a sum of money double in 7 years.
A = P(1 + r)n
10=5(1+r)7
10=5(7+7r)
10=35 + 35r
-25=35r
0.71428 x 100
71%
********
can some one tell me how to do the ones I left blank. Also, i don't understand the per annum, mounthly. Are you supposed to divide the interest rate by 12 to get the new % of interst?
Thanks,
Aka
