Aptitude - True Discount - Discussion

Discussion Forum : True Discount - General Questions (Q.No. 11)
11.
Rs. 20 is the true discount on Rs. 260 due after a certain time. What will be the true discount on the same sum due after half of the former time, the rate of interest being the same?
Rs. 10
Rs. 10.40
Rs. 15.20
Rs. 13
Answer: Option
Explanation:

S.I. on Rs. (260 - 20) for a given time = Rs. 20.

S.I. on Rs. 240 for half the time = Rs. 10.

T.D. on Rs. 250 = Rs. 10.

T.D. on Rs. 260 = Rs. 10 x 260 = Rs. 10.40
250

Discussion:
24 comments Page 2 of 3.

Deepesh samant said:   9 years ago
As we know rt = 1/12.
Rt/2 = 1/24.

T.d = amount * rt / 100 + rt.
= 260 * 1/24 / 100 + 1/24.
= 10.4.

Somesh Saurabh said:   9 years ago
It's very simple.

This kind of situations when we take credit from some bank.

For e.g., let's say I have taken an amount of X i.e. Present Worth(P.W.).

Now I have promised to bank that I am going to pay the amount in T years. So they will tell directly about the total amount I need to pay after T years and this is Total Amount. The Same situation also comes when we sell something to someone who is not able to pay now and instead ask him to pay the amount after some time but at some interest.

For eg. I am to sell my watch at Rs. 1000 to you and you don't have money now to pay so I will tell you to pay rs 1500 after 2 years. It means that PW is 1000 and True Discount is 500.

The rate of interest (R) can be calculated by using simple formula TD = PW * T * R.

P.S. Please go by basics only. Don't use the formulae blindly.

Thank You.

Somesh Saurabh said:   9 years ago
Guys, there is only a little difference between SI and True Discount(TD).
SI is always calculated on the principal amount while TD is always calculated on the PW.

For eg., If the amount g is given as 1000 the SI will be SI = 1000 * R * T.
But for TD, first we need to get PW = (1000 - TD).
Then, TD = (1000 - TD) * R * T.

Hope you guys find it helpful. Thank You.

Pooja said:   1 decade ago
Please elaborate the explanation.

Matlub Sheikh said:   10 years ago
What is SI? Please any one can explain?

Puzeetha said:   10 years ago
Please explain in detail.

Shivangi said:   1 decade ago
What is SI?

Aparna said:   1 decade ago
ptr/100 = SI.

240*tr = 2000.

Then tr = 2000/240.

Then how did you got that 1/12?

Please tell me.

Harini said:   1 decade ago
How S.I and true discount equal?

LARA said:   1 decade ago
First we have to find the value of (R*T) using the formula for PRESENT WORTH.
AMT = PRESENT WORTH + TRUE DISCOUNT.

Then calculate the value for (T/2) i.e., (R*T)/2, using this value and the same amount calculate the new PRESENT WORTH.


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