Money Maths

In simple interest, interest charge on investment or principal money.

In Compound Interest, Interest charge on principal + Accumulated Interest.

Balance after completing 1 years=Balance in the starting + interest after 1 years

For calculating Interest =

First Year’s balance= 25000Rs

First Year’ Interest =

= 2000

Now, balance after the first year= First Year’s balance +First Year’s Interest

= 25000+2000

= 27000Rs

Second Year’s Balance= 27000Rs

Second Year’s Interest=

= 2160Rs

Balance after the second year = Second Year’s Balance + Second Year’s Interest

= 27000+2160

= 29160Rs

In this question we were calculating compound interest, as I mention above interest charge on principal or investment. As you can see I am adding interest in principal value to calculate next year interest.

This Problem is quite similar to the previous one, we will use the same Formula as we used in the previous one.

Balance after completing 1 years=Balance in the starting + interest after 1 years

For calculating Interest =

First Year’s balance= 15000Rs

First Year’ Interest =

= 1800

Now, balance after the first year = First Year’s balance +First Year’s Interest

= 15000+1800

= 16800Rs

Second Year’s Balance= 16800Rs

Second Year’s Interest=

= 2016Rs

Balance after the second year = Second Year’s Balance + Second Year’s Interest

= 16800+2016

= 18816Rs After Paying back 10000, Remaining Balance= 18816-10000

= 8816

Interest on remaining balance =

= 1057.2

Amount Required to settle down the load= 8816+1057.

= 9873.2Rs

Simple Interest=(n=number of years)

SI=

= 20

Amount after 2 years = 200+20

=220

For calculating Interest =

First Year’s balance= 200Rs

First Year’ Interest =

= 200

Now, balance after the first year= First Year’s balance +First Year’s Interest

= 200+10

= 210Rs

Second Year’s Balance= 210Rs

Second Year’s Interest=

= 10.5Rs

Balance after the second year = Second Year’s Balance + Second Year’s Interest

= 210+10.5

= 220.5Rs

Now, we are using the formula to calculate the same.

Amount after n year = investment + CI after n years

= investment

Here, investment = 20000Rs,

rate=6%,

n=3years

Amount after n year =

= 23820.32Rs

Amount after 2 years = investment(1+

= 8000(1+())²

= 10648Rs

She withdraws 5000Rs, Now Remaining Balance= 10648-5000

= 5648Rs

After withdrawing the money, the principal money= 5648

Now, Amount After a year = 5648(1+10/100)¹

(to calculate amount after a year, we can use previous formula).

= 6212.8Rs

Investment = 25000 Rs, rate=11%

Varun Paid Back 10000 Rs after 2 years.

So we need to calculate Amount after 2 years.

Amount after 2 years = 25000(1+11/100)²

= 30802.5 Rs

Varun paid back 10000 Rs

The principal balance will change.

Remaining balance = 30802.5-10000

= 20802.5 Rs

The Amount is 20802.5 Rs.

This amount will change because bank charges 11% interest compounded annually.

After a year amount paid by varun = 20802.5(1+11/100)¹

= 23090.775

.775paisa is rounded to 1 Rupee. Less than .5 are ignored.

=23091 Rs

Investment = 5000 Rs

Arun deposited 5000 Rs in a bank which compound interest half yearly.

Annual rate = 6%

Since Interest is compounded half yearly, Interest has to be calculated twice a year

Half yearly rate = 6/2=3%

We need to figure out the period in which interest compounded.

Amount after a year= 5000(1+3/100)²

= 5304.5 5305(.5paisa rounded to 1Rupee)

Mohan deposited 5000Rs in another bank which compounds interest quarterly.

Annual rate = 6%

Since Interest is compounded quarterly yearly, Interest has to be calculated four times a year.

Quarterly rate = 6/4 =1.5%

Amount after a year= 5000(1+1.5/100)⁴

= 5306.81 5307(.81rounded to 1rupee)

The more amount Mohan would get = 5307-5305 = 2 Rs

Investment = 16000 Rs

Annual rate = 10%

Since Interest is compounded quarterly yearly, Interest has to be calculated four times a year.

Quarterly rate = 10/4=2.5%

Amount after 9 months = 16000(1+2.5/100)³

= 17230.25 Rs

Investment = 15000Rs

Annual rate = 10%

Interest compounded in every 3 months. Interest compounded quarterly yearly.

Since Interest is compounded quarterly yearly, Interest has to be calculated four times a year.

Quarterly rate = 8/4=2%

Amount after a year=

= 16236.482416236

(.48<.5 ignored)

Investment = 2500Rs

Annual rate = 6%

Since Interest is compounded half yearly, Interest has to be calculated twice a year

Half yearly rate = 3%

Amount after a year=

= 2652.25 2652(.25<.5 ignored)

Investment = 30000 Rs

Annual rate = 9%

Since Interest is compounded in every four months, Interest has to be calculated thrice a year

Half yearly rate = 3%

Amount after a year=

= 32781.81 32782(.81paisa rounded to 1rupee)

E-waste in 2014 = 9 crore tons

Initial value = 9 crore to

Rate at which e waste increases every year=15%

It means every year the e waste increases by 15% to its value in that year.

In compound interest, interest charge on the principle and accumulated interest.

This is the same problem as we have solved previously.

E waste in 2020 = 9 crore tons

= 20.8175 crore tons21 crore tons

Initial Price = 8000 Rs

Rate at which price decreases every year = 5%

This is the similar problem as we have solved earlier.

Problem in which decreasing rate is given, actually formula is same that we have used earlier but sign of the rate is negative. Because it is decreasing the principle value will less than the previous year.

Price after two year

= 7220 Rs

Tigers in 2011 = 1700

Rate at number of tigers decreases = 3%

Number of tigers in 2016 =

= 1459.84 1460