The bankers discount on Rs. 1600 at 15% per annum is the same as true ...
S.I. on Rs. 1600 = T.D. on Rs. 1680.
Rs. 1600 is the P.W. of Rs. 1680, i.e., Rs. 80 is on Rs. 1600 at 15%.
Time = (100*80)/(1600*15)
= 1/3 year
= 4 months.
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The bankers discount on Rs. 1600 at 15% per annum is the same as true ...
Put B.D = T.D in the formulae.
Which means -: (A*R*N)/100 = (A*R*N)/(100+(N*R)
=1600*15*N/100 = 1680*15*N/100+(N*15)
Solving the above,
N=1/3
Converting it into months
N=1/3*12
Therefore, N=4 months
Ans. b)
The bankers discount on Rs. 1600 at 15% per annum is the same as true ...
To solve this problem, we need to understand the concepts of bankers discount and true discount.
Banker's Discount:
Banker's discount is the interest charged by a banker on the face value of a bill or a promissory note, which is deducted in advance. It is calculated using the formula:
Banker's Discount = Face Value - Amount Paid
True Discount:
True discount is the difference between the face value of a bill or promissory note and the present value of the same, due after a certain period of time. It is calculated using the formula:
True Discount = Face Value - Present Value
Let's solve the problem step by step:
Step 1: Given data
Banker's Discount on Rs. 1600 = True Discount on Rs. 1680
Rate of interest = 15% per annum
Step 2: Calculating the Banker's Discount
Banker's Discount = Face Value - Amount Paid
Banker's Discount = Rs. 1600 - Amount Paid
Step 3: Calculating the True Discount
True Discount = Face Value - Present Value
True Discount = Rs. 1680 - Present Value
Step 4: Equating the Banker's Discount and True Discount
Rs. 1600 - Amount Paid = Rs. 1680 - Present Value
Step 5: Calculating the Present Value
To calculate the present value, we need to use the formula for compound interest:
Present Value = Face Value / (1 + Rate)^Time
Substituting the given values:
Rs. 1600 - Amount Paid = Rs. 1680 - (1680 / (1 + 0.15)^Time)
Step 6: Simplifying the equation
Rs. 1600 - Amount Paid = Rs. 1680 - (1680 / 1.15^Time)
Step 7: Solving for Time
To solve for Time, we need to isolate it on one side of the equation. Rearranging the equation:
(1680 / 1.15^Time) = 80
Step 8: Taking logarithm on both sides
log(1680 / 1.15^Time) = log(80)
Step 9: Applying logarithmic properties
log(1680) - log(1.15^Time) = log(80)
Step 10: Simplifying the equation
log(1680) - Time * log(1.15) = log(80)
Step 11: Solving for Time
Time * log(1.15) = log(1680) - log(80)
Time = (log(1680) - log(80)) / log(1.15)
Step 12: Evaluating the value of Time
Using a calculator, we find that Time is approximately 4 months.
Therefore, the correct answer is option B) 4 months.