Question

at what percent will a sum of rupees 64000 be compounded to 68921 in 3 years?

Answer 1

The compound interest formula is as follows:

A = P (1 + r/n)ᵃᵇ

Where:

A = The total sum accrued, sum + interest

P = the principal investment amount

 
r = the annual interest rate (decimal)

a = the number of times that interest is compounded per year

b= the number of years the money is invested or borrowed for

Therefore we can use the above information to calculate our rate:

A = 68921
P = 64000
r = ?
a= 1
b= 3

68921 = 64000 ( 1 + r/1) ¹ˣ³


68921 = 64000 ( 1 + r)³

(1+r)³ = 68921/64000 = 1.076890625

(1+r)³ = 1.076890625...........find cube root of both

1+r = 1.025

r = 1.025 - 1

r = 0.025

r = 0.025 x 100% = 2.5%

Therefore the percent rate = 2.5%

Answer 2

Formula for finding Amount

A= P( 1+ R/100)^n

A= Amount in ₹

P= Principal in ₹

R= rate of interest in %

n= time period in years


Given:

A= ₹68921, P= ₹64000, n= years

A= P( 1+ R/100)^n

68921 = 64000 (1+ R/100)³

68921/64000 = (1+R/100)³

(41/40)³ = (1+R/100)³

[68921= 41³, 64000= 40³]

41/40 = (1+R/100)

41/40 - 1= R/100

(41-40)/40 = R/100

1/40 = R/100

40R= 100

R= 100/40= 10/4= 5/2= 2.5%

R= 2.5%


Rate percent = 2.5%

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Hope this will help you...