# Aptitude - Simple Interest - Discussion

Discussion Forum : Simple Interest - Data Sufficiency 2 (Q.No. 1)

*Directions to Solve*

Each of the questions given below consists of a question followed by three statements. You have to study the question and the statements and decide which of the statement(s) is/are necessary to answer the question.

1.

What is the principal sum? | |

I. | The sum amounts to Rs. 690 in 3 years at S.I. |

II. | The sum amounts to Rs. 750 in 5 years at S.I. |

III. | The rate of interest is 5% p.a. |

Answer: Option

Explanation:

Clearly, any two of the three will give us the answer.

Correct answer is (E).

Discussion:

31 comments Page 1 of 4.
HRK said:
2 years ago

Using I and III;

Let S.I be 'x'.

Hence, P = 690 - x.

x = [(690- x) *5*3] / 100.

Solve for 'x' and find P.

Similarly, it works using II and III

Now, using I and II.

Let x be the interest rate.

Hence, P + 3Px = 690, simplify to P(1+3x) =690 -----> (a)

P + 5Px = 750, simplify to P(1+5x)=750 -----> (b).

Now dividing a by b, P gets canceled and solves for x.

x = 0.05 or 5%.

Now substitute x in the equation a or b to get P.

So we can use any of the three to solve.

Thanks.

Let S.I be 'x'.

Hence, P = 690 - x.

x = [(690- x) *5*3] / 100.

Solve for 'x' and find P.

Similarly, it works using II and III

Now, using I and II.

Let x be the interest rate.

Hence, P + 3Px = 690, simplify to P(1+3x) =690 -----> (a)

P + 5Px = 750, simplify to P(1+5x)=750 -----> (b).

Now dividing a by b, P gets canceled and solves for x.

x = 0.05 or 5%.

Now substitute x in the equation a or b to get P.

So we can use any of the three to solve.

Thanks.

(3)

Karuppaiya said:
3 years ago

As Simple as Like that, I will explain here;

Given as Statement 1: P = 690 N= 3 yrs.

Given as Statement 2: P = 750 N= 5 yrs.

By Using these statements We get SI for 2 yrs is (750-690 = 60).

Therefore; SI for 1 yr is 30.

So, SI for 3 yrs will be 90 and that of for 5 yrs will be 150.

We know that Amount = Principal + SI.

Here for 3 yrs W.K.T SI is 90 and Amount is 690.

and therefore Principal is 690-90=600.

And by using statements 2 and 3 we can solve by the following method.

P + (P*5*5)\100 = 750.

100P + 25P = 750*100.

125P = 75000.

P = 600.

Given as Statement 1: P = 690 N= 3 yrs.

Given as Statement 2: P = 750 N= 5 yrs.

By Using these statements We get SI for 2 yrs is (750-690 = 60).

Therefore; SI for 1 yr is 30.

So, SI for 3 yrs will be 90 and that of for 5 yrs will be 150.

We know that Amount = Principal + SI.

Here for 3 yrs W.K.T SI is 90 and Amount is 690.

and therefore Principal is 690-90=600.

And by using statements 2 and 3 we can solve by the following method.

P + (P*5*5)\100 = 750.

100P + 25P = 750*100.

125P = 75000.

P = 600.

(2)

Manthan said:
3 years ago

As Amount = principal+ SI.

Where si= prt/100.

This is the basic formulae that are applied here.

If suppose we take equationn 1 and 2 then,

P + P.3.r% = 690---(1)

P + P.5.r% = 750---(2)

Divide equation 1 by 2 to get r and then p,

And if we take eqn 1 and eqn 3 we will get;

"P=(100*si)/(r*t) ".

Where si= prt/100.

This is the basic formulae that are applied here.

If suppose we take equationn 1 and 2 then,

P + P.3.r% = 690---(1)

P + P.5.r% = 750---(2)

Divide equation 1 by 2 to get r and then p,

And if we take eqn 1 and eqn 3 we will get;

"P=(100*si)/(r*t) ".

Vidya sree said:
3 years ago

Thank you @Ashish.

Effoti said:
6 years ago

By using I and II;

S.I for 2 years = 750-690 = 60 as S.I is divided uniformly for each year, For 1 year = Rs. 30 and For 3 year = 90,

Principal = 690-90 = 600.

By using II and III

As Total Sum = Principal + Interest i.e 750 = P + I (after 5 years) ------> (1)

P = I *100 / R * T = I *100 / 5*5 = 4I,

Put value of P in eq. 1, 750 = 5I , I = 150 and P = 750 -150 = Rs. 600,

Similarly By using I and III.

P = I *100 / R*T = I*100/5*3 = 20/3(I),

690 = 20/3(I) + I , By solving this we get I = Rs.90 and P = 690 - 90 = Rs. 600.

Hence answer is E Any two of the three.

S.I for 2 years = 750-690 = 60 as S.I is divided uniformly for each year, For 1 year = Rs. 30 and For 3 year = 90,

Principal = 690-90 = 600.

By using II and III

As Total Sum = Principal + Interest i.e 750 = P + I (after 5 years) ------> (1)

P = I *100 / R * T = I *100 / 5*5 = 4I,

Put value of P in eq. 1, 750 = 5I , I = 150 and P = 750 -150 = Rs. 600,

Similarly By using I and III.

P = I *100 / R*T = I*100/5*3 = 20/3(I),

690 = 20/3(I) + I , By solving this we get I = Rs.90 and P = 690 - 90 = Rs. 600.

Hence answer is E Any two of the three.

Mansi Arora said:
6 years ago

Hi @Aryan,

We are using here all the three given statements to get the value of P which is not given in the options.

We are using here all the three given statements to get the value of P which is not given in the options.

P V Snehil said:
6 years ago

We cannot get P using I and II, as we donot know the are when we have only these two statements.

Correct answer is D.

Correct answer is D.

(1)

Shruthi said:
6 years ago

If it is any two of the 3 then there is a possibility of taking 1 and 2.

How can we get p using 1 and 2?

How can we get p using 1 and 2?

Girish said:
7 years ago

690 - P = 3PR.

750 - p = 5PR.

Dividing both equations

(690 - P)/(750 - P) = 3/5.

-> (690 - P)5 = (750 - P)3.

By solving;

P = 600.

750 - p = 5PR.

Dividing both equations

(690 - P)/(750 - P) = 3/5.

-> (690 - P)5 = (750 - P)3.

By solving;

P = 600.

(1)

T.Prabhu Pandiyan. said:
8 years ago

Anyone can please help me to understand the question.

(1)

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