RRB NTPC - Simple Interest

1.

If the simple interest on Rs. 1120 for 2 years is Rs.8000/-, what is the rate of interest percent per annum? 

   A.) 4%
   B.) 7%
   C.) 8%
   D.) 5%

Answer: Option 'B'

I = Rs.1120/- 
T = 2 years 
P = Rs.8000/- 
R = ? 
S.I = (P×T×R/100) 
R = (S.I×100)/(P×T) 
R = (1120×100)/(8000×2) 
R = 56/8 = 7% 

2.

A man borrowed some amount, after 3 years he paid Rs.10,400/- with 10% interest, then how much Amount he borrowed? 

   A.) Rs.7000/-
   B.) Rs.8000/-
   C.) Rs.9000/-
   D.) Rs.1000/-

Answer: Option 'B'

principal P = ? 
Rate of interest R = 10% 
Time T = 3 years 
Accumulated Amount A = Rs.10400/- 
A = P + I 
A = P + PTR/100 
A = P(1+ TR/100) 
Rs.10400/- = P [1 + 3*10/100] 
Rs.10400/- = P [1/1 + 3/10] 
Rs.10400/- = P [10+3/10] = P[13/10] 
Rs.10400/- = P * 13/10 
==> P = Rs.104000/13 
==> P = Rs.8000/- 

3.

A man took some money for borrowed, for 3 years the total will be Rs.4000 and 5 years it will be Rs.5000/-. Then how much amount he borrowed? 

   A.) Rs.500/-
   B.) Rs.1500/-
   C.) Rs.2500/-
   D.) Rs.1000/-

Answer: Option 'C'

3 years --------> Rs.4000/- 
5 years --------> Rs.5000/- 
~                    ~
------------------------------  
2 years ----> Rs.1000/- 
1 year  -----> Rs.500/-  
3 years × Rs.500/- = Rs.1500/- 
P = Rs.4000/- - Rs.1500/- = Rs.2500/- 
P = Rs.2500/-

4.

A borrow took by a man, for every 8 years it will be 3 times, then what is the rate of the interest?

   A.) 15%
   B.) 20%
   C.) 25%
   D.) 28%

Answer: Option 'C'

P = 1 , I = 2 , T = 8years R = ? 
I = PTR/100 
2 = 1×8×R/100 
R = 25% 

5.

A man took some money for borrowed, for 2 years the total will be Rs.9000/- and 5 years it will be13, Rs.500/-. Then how much amount he borrowed? 

   A.) Rs.4500/-
   B.) Rs.6000/-
   C.) Rs.5000/-
   D.) Rs.5500/-

Answer: Option 'B'

2 years --------> Rs.9000/- 
5 years --------> Rs.13500/- 
~                 ~
-----------------------------  
3 years ----> Rs.4500/- 
1 year -----> Rs.1500/-  
2years × Rs.1500/- = Rs.3300/- 
P = Rs.9000/- - Rs.30000/- = Rs.6000/- 
P = Rs.6000/- 

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