Open in App
Solution
Let sum of money be P=100
Interest per annum =10%
amount = 2× 100 = 200
simple interest = 200 - 100 = 100
Since,
SI=PTR100
⇒T=100×SIPR
=100×100100×10
∴t=10 years.
Similar questions
Q. A certain sum of money lent out at a certain rate of interest per annum,
doubles itself in 10 years. In how many years will it treble itself?
Q. In how many years will a sum of money double itself at 4% per annum ?
Q. At what rate percent per annum simple interest will a sum of money double itself in 6 years?
Q. A sum of money lent out at C.I. at a certain rate per annum doubles itself in 5 years. Find in how many years will the money become eight times of itself at the same rate of interest p.a.
Q. At what rate percent per annum will a sum of money double itself in 10 years.
View More
A. 8 years
B. 10 years
C. 12 years
D. 14 years
Solution(By Examveda Team)
$$\eqalign{ & {\text{Let principal = P}} \cr & \therefore {\text{amount = 3P}} \cr & {\text{Interest = 3P}} - {\text{P}} \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,{\text{ = 2P}} \cr & {\text{According to the question,}} \cr & {\text{2P = }}\frac{{{\text{P}} \times {\text{R}} \times
{\text{20}}}}{{100}} \cr & \Rightarrow {\text{R = 10% }} \cr} $$
Let after t years it will become double
$$\eqalign{ & {\text{Hence,}} \cr & {\text{Interest = 2P}} - {\text{P = P}} \cr & \Rightarrow {\text{P = }}\frac{{{\text{P}} \times 10 \times {\text{t}}}}{{100}} \cr & \Rightarrow {\text{t = 10 years}} \cr} $$
Given that, the sum of money triples itself in 20 years
∴ P + I = 3P
∴ I = 2P
and T = 20 years
Now simple interest I = `"PRT"/100`
∴ 2P = `("P" xx "R" xx 20)/100`
∴ R = 10
∴ Rate of interest = 10% per annum
The time period is to be calculated for the condition that the sum doubles itself i.e. for the condition
P + I = 2P
i.e. I = P
i.e. `("P" xx "R" xx "T")/100 = "P"`
∴ `(10 xx "T")/100 = 1`
∴ T = 10
∴ The sum will become double of itself in 10 years.
A sum of money at simple interest doubles in 10 years. In how many years, at the same rate, will it be tripled?
This question was previously asked in
UPTET 2018 Paper-1 (Hindi - English/Sanskrit) Hinglish Solution
View all UPTET Papers >
- 30 years
- 25 years
- 20 years
- 15 years
Answer (Detailed Solution Below)
Option 3 : 20 years
Free
10 Questions 10 Marks 7 Mins
GIVEN:
Amount = 2P
Time = 10 years
FORMULAE USED:
SI = (PRT/100)
Amount = (PRT/100) + P
CALCULATION:
Amount = (PRT/100) + P
2P = (PR/10) + P
⇒ P = (PR/10)
⇒ R = 10%
According to question, Amount = 3P
3P = (10PT/100) + P
⇒ 2P = (PT/10)
⇒ T = 20 years
∴ Time taken to triple the amount is 20 years.
Interest = 2P - P = P = 100% of principle
Time = 10 year
Hence, rate = Interest/Time = 100/10 = 10%
New interest = 3P - P = 2P = 200% of principle
∴ Time = Interest/Rate = 200/10 = 20 Years
Last updated on Sep 21, 2022
The RRB (Railway Recruitment Board) has released the Result, and Cut Off marks for the CBAT (Computer Based Aptitude Test) stage for Pay Level 6. The result and cut-off marks are announced for the RRB Chandigarh, Bhopal & Chennai regions for the recruitment cycle 2021. The exam is conducted to fill up a total number of 35281 vacant posts. Candidates who are qualified for the Computer Based Aptitude Test will be eligible for the next round, which will be Document Verification & Medical Exam. The candidates with successful selection under RRB NTPC will get a salary range between Rs. 19,900 to Rs. 35,400. Know the RRB NTPC Result here.
Ace your Interest preparations for Simple Interest with us and master Quantitative Aptitude for your exams. Learn today!