Aptitude - Simple Interest - Discussion
Discussion Forum : Simple Interest - General Questions (Q.No. 9)
9.
A sum of Rs. 725 is lent in the beginning of a year at a certain rate of interest. After 8 months, a sum of Rs. 362.50 more is lent but at the rate twice the former. At the end of the year, Rs. 33.50 is earned as interest from both the loans. What was the original rate of interest?
Answer: Option
Explanation:
Let the original rate be R%. Then, new rate = (2R)%.
Note:
Here, original rate is for 1 year(s); the new rate is for only 4 months i.e. 
year(s).
 |
 |
725 x R x 1 |  |
+ | |
362.50 x 2R x 1 | |
= 33.50 |
| 100 | 100 x 3 |
(2175 + 725) R = 33.50 x 100 x 3
(2175 + 725) R = 10050
(2900)R = 10050
| R = |
10050 | = 3.46 |
| 2900 |
Original rate = 3.46%
Discussion:
97 comments Page 10 of 10.
Suman said:
1 decade ago
Let the original rate is r%, then new rate is 2r.
here original rate is for only 8 months i.e 2/3; new rate is for 4 month i.e 1/3year(s).
=>{(725*r*2)/(100*3)}+{(362.50*2r*1)/(100*3)}=33.50
=>4.8333333333r+2.4166666667r=33.50
=>7.25r=33.50
=>r=33.50/7.25
=>r=4.6206896552
i.e original rate=4.62%
here original rate is for only 8 months i.e 2/3; new rate is for 4 month i.e 1/3year(s).
=>{(725*r*2)/(100*3)}+{(362.50*2r*1)/(100*3)}=33.50
=>4.8333333333r+2.4166666667r=33.50
=>7.25r=33.50
=>r=33.50/7.25
=>r=4.6206896552
i.e original rate=4.62%
Supriya said:
1 decade ago
I think the correct solution is as follows:
1) consider P=725, R=r, n= 8 months
SI= [725*(8/12)*r]/100= 4.833r
Amount= SI+P
Amount= 4.833r+725
this amount will be principle for next step
2) P= (4.833r+725)+362.5 = 1087.5+4.833r
R= 2r, n=4 months
SI= [ (1087.5+4.883r)*(4/12)*2r]/100 = 33.5
solving this r= 4.529%
Is this solution correct....??
please suggest me..!!
1) consider P=725, R=r, n= 8 months
SI= [725*(8/12)*r]/100= 4.833r
Amount= SI+P
Amount= 4.833r+725
this amount will be principle for next step
2) P= (4.833r+725)+362.5 = 1087.5+4.833r
R= 2r, n=4 months
SI= [ (1087.5+4.883r)*(4/12)*2r]/100 = 33.5
solving this r= 4.529%
Is this solution correct....??
please suggest me..!!
Aakash said:
1 decade ago
After reading it carefully I got it Tarun.
The rate of interest which is twice in case of 362.50 is twice only for 362.50 and not for (725+ 362.50)/
Second thing ---> don't take this question as a single 1. See both the problems with different view.
Rs 725 is not taken back it is uniform through out the year.
Still any kind of queries are welcomed.
The rate of interest which is twice in case of 362.50 is twice only for 362.50 and not for (725+ 362.50)/
Second thing ---> don't take this question as a single 1. See both the problems with different view.
Rs 725 is not taken back it is uniform through out the year.
Still any kind of queries are welcomed.
Meenakshie said:
1 decade ago
For the 8 month principal should be (725+362.50)=1087.50
Tarun said:
1 decade ago
In question,just after 8 month,,principal change..725 only for 8 month..so its SI should b claculated only for 8 month and thn..for next 4 month the toatal amount(725+362.50) sholud consider as next 4 month principal..at rate 2R..
Shubhra said:
1 decade ago
(725 x R x 1 /100) + (362.50 x 2R x 1 /100 x 3 ) = 33.50
(725 x 1 /100 + 362.50 x 2 /100 x 3) R = 33.50
(725 x 3 + 725 / 100 x 3) R = 33.50
(2175 + 725 ) R = 33.50 x 100 x 3
(2900) R = 10050
R = 10050/2900
R = 3.46%
(725 x 1 /100 + 362.50 x 2 /100 x 3) R = 33.50
(725 x 3 + 725 / 100 x 3) R = 33.50
(2175 + 725 ) R = 33.50 x 100 x 3
(2900) R = 10050
R = 10050/2900
R = 3.46%
Abhiruchi said:
1 decade ago
How
725 x R x 1
-------------
100
become 2175
725 x R x 1
-------------
100
become 2175
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