Saving
The power of compounding grows your savings faster Show
3 minutes
The sooner you start to save, the more you'll earn with compound interest. Compound interest is the interest you get on:
For example, if you have a savings account, you'll earn interest on your initial savings and on the interest you've already earned. You get interest on your interest. This is different to simple interest. Simple interest is paid only on the principal at the end of the period. A term deposit usually earns simple interest. Save more with compound interestThe power of compounding helps you to save more money. The longer you save, the more interest you earn. So start as soon as you can and save regularly. You'll earn a lot more than if you try to catch up later. For example, if you put $10,000 into a savings account with 3% interest compounded monthly:
Compound interest formulaTo calculate compound interest, use the formula: A = P x (1 + r)n A = ending balanceP = starting balance (or principal)r = interest rate per period as a decimal (for example, 2% becomes 0.02) n = the number of time periods How to calculate compound interestTo calculate how much $2,000 will earn over two years at an interest rate of 5% per year, compounded monthly: 1. Divide the annual interest rate of 5% by 12 (as interest compounds monthly) = 0.0042 2. Calculate the number of time periods (n) in months you'll be earning interest for (2 years x 12 months per year) = 24 3. Use the compound interest formula A = $2,000 x (1+ 0.0042)24A = $2,000 x 1.106 A = $2,211.64
Lorenzo and Sophia compare the compounding effect
Lorenzo and Sophia both decide to invest $10,000 at a 5% interest rate for five years. Sophia earns interest monthly, and Lorenzo earns interest at the end of the five-year term. After five years:
Sophia and Lorenzo both started with the same amount. But Sophia gets $334 more interest than Lorenzo because of the compounding effect. Because Sophia is paid interest each month, the following month she earns interest on interest.
Principal: The money which we deposit in or the lower from the bank or the money learned called the principal. Rate of interest: The interest paid on $ 100 for one year is called the rate per cent per year or rate per cent per annum. Time: The period of time for which the money is lent or invested. Interest: Additional money paid by the borrowed to the lender for using the money is called interest. Simple Interest: If the interest is calculated uniformly on the original principal throughout the lone period, it is called simple interest. Amount: The total money paid back to the lender is called the amount. Calculate Simple Interest Formula to calculate Simple Interest?If P denotes the principal ($), R denotes the rate (percentage p.a.) and T denotes time (years), then:- S.I = (P × R × T)/100
R = (S.I × 100)/(P × T) P = (S.I × 100)/(R × T) T = (S.I × 100)/(P × R) If the denotes the amount, then A = P + S.I
Note: ● When we calculated the time period between two dates, we do not could the day on which money is deposited but we count the day on which money is retuned. ● Time is always taken according to the per cent rat. ● For converting time in days into years, divide th number of days by 365 (for ordering or lap year.) ● For converting time in month into years, divide th number of month by 12 (for ordering or lap year.) Examples to find or calculate simple interest when principal, rate and time are knownCalculate Simple Interest Find the simple interest on: (a) $ 900 for 3 years 4 months at 5% per annum. Find the amount also. Solution: P = $ 900,R = 5% p.a. T = 3 years 4 months = 40/12 years = 10/3 years Therefore, S.I = (P × R × T)/100 = (900 × 5 × 10)/(100 × 3) = $ 150 Amount = P + S.I = $ 900 + $ 150 = $ 1050
Solution: P = $ 1000,R = 4% p.a. T = 6 months = 6/12 years S.I = (P × R × T)/100 = (1000 × 4 × 1)/(100 × 2) = $ 20 Therefore, A = P + I = $( 1000 + 20) = $ 1020
Solution: P = $ 5000, R = 151/2% p.a. T = 146 days S.I = ( 5000 × 31 × 146)/(100 × 2 × 365) = $ 10 × 31 = $ 310
Solution: P = $ 1200, R = 10% p.a. T = 9th April to 21st June= 73 days [April = 21, May = 31, Jun = 21, 73 days] = 73/365 years S.I = (1200 × 10 × 73)/(100 × 365) = $ 24 Examples to find or calculate Time when Principal, S.I and Rate are knownCalculate Simple Interest 1. In how much time dose $ 500 invested at the rate of 8% p.a. simple interest amounts to $ 580. Solution: Here P = $ 500, R = 8% p.a A = $ 580Therefore S.I = A - P = $ (580 - 500) = $ 80 Therefore T = (100 × S.I)/(P × R) = (100 × 80)/(500 × 3) = 2 years 2. In how many years will a sum of $ 400 yield an interest of $ 132 at 11% per annum? Solution: P = $ 400, R = 11% S.I = $ 132 T = (100 × S.I)/(P × R) = (132 × 100)/(400 × 11) = 3 yearsCalculate Simple Interest 3. In how many years will a sum double itself at 8 % per annum? Solution: Let Principal = P, then, Amount = 2PSo , S.I. = A - P = 2P – P = P T = (100 × S.I)/(P × R) = ( 100 × P)/(P × 8) = 25/2 = 121/2 years
4. In how many years will simple interest on certain sum of money at 6 1/4% Per annum be 5/8 of itself? Solution: Let P = $ x, then S.I = $ 5/8 x Rate = 6 1/4% = 25/4 % Therefore T = ( 100 × S.I)/(P × R) = ( 100 × 5/8)/(x × 25/4) x = ( 100 × 5 × x × 4)/(x × 8 × 25)T = 10 years Examples to find or calculate Rate per cent when Principal, S.I. and Time are known1. Find at what rate of interest per annum will $ 600 amount to $ 708 in 3 years. Solution: P= $ 600 , A = $ 708 Time = 3 years Therefore S.I. = $ 708 - $ 600 = $ Rs. 108 Now, R = ( 100 × S.I)/(P × R) = (100 × 108)/(600 × 3) = 6% p.a.Calculate Simple Interest 2. Simple interest on a certain sum is 36/25 of the sum. Find the Rate per cent and time if they are both numerically equal. Solution: Let the Principal be $ X Then S.I. = 36/25 x R = ? T = ? Let Rate = R % per annum, then Time = R years. So S.I. = (P × R × T)/100 → 36/25 x = (x × R × T)/100 --- ( 36 × 10 × x)/(25 × x) = R2 ----- R2 = 36 × 4 ----- R = √(36 × 4) = 6 × 2 Therefore Rate = 12 % p.a. and T = 12 years
3. At what rate per cent per annum will $ 6000 produce $ 300 as S.I. in 1 years? Solution: P= $ 600, T = 1 year S.I. = $ 300 Therefore R = ( S.I × 100)/(P × R) = ( 300 × 100)/(6000 × 1) = 5% p.a4. At what rate per cent per annum will a sum triple itself in 12 years ? Solution: Let the sum be $ P, then Amount = $ 3P S.I. = $ 3P – P = $ 2P, Time = 12 years Now, R =( S.I × 100)/(P × R) = (100 × 2P)/(P × 12) = 50/3 = 16.6 %Examples to find or calculate Principal when Rate, Time and S.I. are knownCalculate Simple Interest 1. What sum will yield $ 144 as S.I. in 21/2 years at 16% per annum? Solution: Let P = $ x, S.I. = $ 144 Time = 21/2 years or 5/2 years, Rate = 16% So, P = ( 100 × S.I)/(P × R) = ( 100 × 144)/(16 × 5/2) = ( 100 × 144 × 2)/(16 × 5) = $ 3602. A some amount to $ 2040 in 21/2 years at , P = ? Solution: Let the principal = $ x S.I. = $ (x × 11 × 5/2 × 1/100) = $ 11x/40 Amount = P + S.I. = x/1 + 11x/40 = (40x × 11x)/40 = 51x/40 But 51x/40 = 204051x = 2040 × 40 ---- x = (2040 × 40)/51 = $ 1600
3. A certain sum amounts to $ 6500in 2 years and to $ 8750 in 5 years at S.I. Find the sum and rate per cent per annum. Solution: S.I. for 3 years = Amount after 5 years – Amount after 2 years = $ 8750 – $ 6500 = 2250 S.I. for 1 years = Rs. 2250/3 = $ 750 Therefore S.I. for 2 years = $ 500× 2 = $ 1500 So, sum = Amount after 2 years – S.I.for 2 years = $ 6500- 1500 = $ 5000 Now, P = Rs.5000, S.I. = $ 1500, Time = 3 years R = ( 100 × S.I)/(P × T) = (100 × 1500)/(5000 × 2) = 15% Therefore The sum is $ 5000 and the rate of interest is 15%
Solution: Let the first part be $ x. Second part = $ (6500 - x ) Now S.I. on $ X at 9% per annum for 1 year = $ (x × 9 × 1)/100 = 9x/100 S.I. on $ (6500 – x ) at 10% per annum 1 year = $ ((6500-x) × 10 × 1)/100 = $ ((6500 - x))/10 Total S.I = $ (9x/100+ (6500 - x)/10) = ((9x + 6500 - 10x)/100) = $ ( 65000 - x)/100But given that total S.I.= $ 605 So, (6500 - x)/100 =605 -----65000 - x = 60500 ----- 65000 – 60500 = x ---- x = $ 4500 Now, second part = 6500 – x = 6500 – 4500 = $ 2000 Hence, first part = $ 2000 and second part = $ 4500
Solution: Let the original deposits be $ xThen, S.I. on $ x for 1 year at (10 - 9 )% = 1% per annum + S.I. on $ 500 For I year at 10% per annum = $ 15 ----- ( x × 1 × 1)/100 + ( 500 × 10 × 1)/100 = 150 ----- x/(100 ) + 50 = 150 ---- x/(100 ) + 150 – 50 ----- x/(100 ) + 100 ----- x = 100 × 100 = $
10,000 Therefore, the original deposit is $ 10,000. Calculate Simple Interest ● Simple Interest What is Simple Interest? Calculate Simple Interest Practice Test on Simple Interest ● Simple Interest - Worksheets Simple Interest Worksheet 7th Grade Math Problems 8th Grade Math Practice From Calculate Simple Interest to HOME PAGE
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