Question

A certain sum of money amounts to Rs 1125 in 5 years and to Rs1200 in 8 years. Find the sum

Answer 1

Interest of 3 years = 1200-1125= 75

interest ..........1year= 75/3=25
interest .........5 years = 125

so the sum is 1000.
$sum = \: amount - interest \\ = = = =1125 - 125 \\ 1000$

Answer 2

Sum is Rs 1000 if it amounts to Rs 1125 in 5 years and to Rs1200 in 8 years.

Given:

• A certain sum of money amounts to Rs 1125 in 5 years
• Amount to Rs 1200 in 8 years

To Find:

• Sum

Solution:

• SI = P * R * T /100
• A = P + SI  = P +  P * R * T /100
• P = Principal ( Sum)
• R + rate of Interest
• T = Time
• SI = Simple Interest
• A = Amount

Step 1:

Substitute T = 5 and A = 1125  in the formula A = P +  P * R * T /100

1125 = P + P * R * 5/100        Eq1

Step 2:

Substitute T = 5 and A =1200  in the formula A = P +  P * R * T /100

1200 = P + P * R * 8/100         Eq2

Step 3:

Eq2 - Eq1

=> 75  =  8PR/100 - 5PR/100

=> 75 = 3PR/100

=> PR = 2500

Step 4:

Substitute PR = 2500 in Eq1 and solve for P

1125 = P + 2500 * 5/100

=> 1125 =P + 125

=> P = 1000

Hence, Sum is Rs 1000