Aptitude - Decimal Fraction - Discussion

Discussion :: Decimal Fraction - General Questions (Q.No.14)

14. 

The price of commodity X increases by 40 paise every year, while the price of commodity Y increases by 15 paise every year. If in 2001, the price of commodity X was Rs. 4.20 and that of Y was Rs. 6.30, in which year commodity X will cost 40 paise more than the commodity Y ?

[A]. 2010
[B]. 2011
[C]. 2012
[D]. 2013

Answer: Option B

Explanation:

Suppose commodity X will cost 40 paise more than Y after z years.

Then, (4.20 + 0.40z) - (6.30 + 0.15z) = 0.40

0.25z = 0.40 + 2.10

z = 2.50 = 250 = 10.
0.25 25

X will cost 40 paise more than Y 10 years after 2001 i.e., 2011.


Jamal said: (Jul 23, 2010)  
I did not understand this problem. So I want to know detail about this. Some one help me out please.

E.Shanthi Krishna said: (Sep 27, 2010)  
Hey, the logic what you mentioned here is right but when I'm calculating by year to year basis the answer found to be as 2013.

But your answer is 2011. How?

Raj said: (Dec 9, 2010)  
In 2011 x commodity will be 8.20 &y will be 7.95 i.e 0.35 paise more than y.....

Vimal said: (Feb 7, 2012)  
a+(n-1)d = arithmetic progression
4.20+(n-1).40 = 6.30+(n-1).15 + .0
n-1 = 10;
n =11;
check the result..is it correct?

Manpreet Singh said: (Jun 17, 2013)  
Hey guys there is a very easy trick to solve such type of problems.

Now take y as constant at 6.30 and see the difference in the increase i.e., 40-15=25.

Now increase .25 into 4.20 till it reaches near 6.30. so, in 2010 it reaches to 6.45.

Now, in 2011 increase as given in the question.

As .15 into 6.30 = 6.45 and .40 into 6.45 = 6.85 in 2011 so, .40 increased in 2011.

Narasinga Rao said: (Oct 6, 2013)  
Logic - 40 ps * 10 yrs = 4 Rs (Rs 4.20 + Rs 4) = 8.20 Rs.

15 ps * 10 yrs = 1.50 Rs/Ps (Rs 6.30 + Rs 1.50)= 7.80 Rs.

8.20 - 7.80 = 40ps.

yr 2001
10 yrs
----
yr 2011 Answer.
----

Moses said: (Feb 10, 2015)  
Why calculate using 0.40 as the increase after time z and 40 as given in the question?

Renuka Prasad said: (Aug 21, 2015)  
= {(6.30-4.20)+0.40}/0.40-0.15.
= 2.50/0.25.
= 10 year.

Himanshi Sethi said: (Sep 19, 2015)  
@Moses.

They just convert paise into rupees.

Sankara Gomathi said: (Mar 2, 2016)  
Very clear this answer.

Thank you.

Animesh said: (Apr 25, 2017)  
I solved by using arithmetic progression.

4.20+(n-1)0.40 = 6.30+(n-1)0.15 + 0.40.

And the answer which came is 11 i.e 2012.

Minar said: (May 10, 2017)  
4.20 + (.4*10) = 8.2.
6.30 + (.15*10) = 7.8.

How could it be 10 yrs?

Om Singh said: (Dec 25, 2017)  
4.20+.40z=6.30+.15z+.40,
.25z=2.10+.40,
Z=10.

Monisa said: (Dec 29, 2017)  
40 paise converted to rupees as 0.40 . each year x increase 0.4 and each year Y increase 0.15 so,
Year ---------------> X ----- Y
2001 ------------ 4.2 ----- 6.3
2002 ------------4.6 ----- 6.45
2003 ------------5 ----- 6.6
2004 ------------5.4 ----- 6.75
2005 ------------5.8 ----- 6.9
2006 ------------6.2 ----- 7.05
2007 ------------6.6 ----- 7.2
2008 ------------7 ----- 7.35
2009 ------------7.4 -----7.5
2010 ------------ 7.8 -----7.65
2011 ------------8.2 ----- 7.8

Convert it into rupees
X Y
820 780
their difference (820-780)=40.
therefore ans is 2011.

Jyothi said: (Sep 28, 2018)  
Very clear answer, Thanks all.

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