F.1 Mathematics Homework (15)

2013-12-21 10:40 pm

1. Lydia deposits $165 000 in a bank at an interest rate of 5.25% p.a. simple
interest. Find
(a) the amount received after 7 months, correct to the nearest $10,
(b) the time required to get the simple interest $23 100.

2. How long will a sum of money double itself if simple interest is calculated at an interest rate of 8% p.a. ?

3. Agnes deposits $9 000 in a bank at an interest rate of R% p.a. simple interest. If the interest rate changes to 5.5% p.a., Agnes will get $270 more after 2 years. Find the value of R.

4.Jacky borrows $40 000 from a bank where simple interest is calculated at an
interest rate of R% p.a. Find the value of R in each of the following.
(a) The interest is 3/4 of the original principal after 15 years.
(b) The amount is 3 times the original principal after 20 years.

steps and answers. 15 points.
thx

回答 (1)

用戶4366

2013-12-22 12:00 am

✔ 最佳答案

1.a)
165000(1+0.0525×7/12) = 170050

b)
23100 = 165000(0.0525×n/12)
n = 32 months

2. 2P = P(1+0.08×n)
2 = (1+0.08×n)
1 = 0.08×n
n = 1/0.08
n = 12.5 years

3. Interest at R% p.a. for 2 years for a capital of 9000
= 9000(R/100)×2
Interest at 5.5% p.a. for 2 years for a capital of 9000
= 9000(5.5/100)×2 = 990

990 - 9000(R/100)×2 = 270
990 - 270 = 9000(R/100)×2
720 = 180R
R = 4%

4. a)
(40000)(3/4) = 40000(R/100)×15
30000 = 400R×15
R = 5%

b)
3(40000) = (40000)(1+R×20/100)
3 = (1+R×20/100)
2 = R×20/100
200/20 = R
R = 10%

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