Aptitude - Profit and Loss - Discussion

Thanks @Satish.

Suppose c.p = x,
SP = 2x.
profit = 2x - x =x.
Profit % = (profit/ c.p )* 100 => (x / x) * 100.
Hence profit% = 100.

The price of a commodity becomes tripled in 20 years. Find the average rate of increase.

This solution is;

Because in the question profit or gain is being mentioned.

So G(Gain) = Sp(selling price) - Cp(cost price) ------> (1)
Or eq.(1) can also be written as;
Sp = (G+Cp) ------> (2).

And by what the question says we can make an equation as follows;
3G = 2Sp - Cp ------> (3)

Eq(2) in eq(3) and after solving eq(3).
We get G=Cp ------> (4).

Now in Gain% formula.
G% = (G*100)/Cp ------> (5).
Put the value of eq(4) in (5).
And G% equals to 100 (The answer).

I think the simplest solution is this.

As we know (Profit %) = (S.P - C.P) * 100 / C.P ---> EQUATION 1

In question say S.P is doubled & Profit is Tripled(not Profit %)

So Assume C.P= C S.P= S Profit = P.

As we know Profit = S.P - C.P.
So P = S - C ---> Eqn.1
As given Sale price is doubled & Profit is Tripled
So 3P=2S-C ---> Eqn.2

By solving this both Eqn. we get S=2C Means SP=2CP.

Put this value in starting Equation 1 you'll get 100% as answer.

Its so easy to solve the problem:

Firstly,we assume the C.P be x Rs. ( i.e c.p = x Rs )
That mean S.P is doubled of c.p i.e 2x Rs. ( i.e s.p = 2x Rs )
Then profit = s.p - c.p.
= 2x -x.
profit = x rs.

Then, profit % = (profit * 100 /c.p).
= (x *100 / x),
profit% = 100 rs.

Let c.p =100 rs , then s.p=200,
Profit = 200-100=100.
%profit = 100*100/100=100%,
Profit becmes three times i.e 100 * 3 = 300.

Let's, c.p = x;
so, s.p = 2x;
profit = s.p - c.p.
So profit = 2x - x =x;
Profit % = (profit/ c.p )* 100 => (x / x) * 100.
So, profit % is 100.

Dear sir,

Here,if cp=x, sp=y.

Then according to question profit will be;
Profit =(y-x),
Here, 3(y-x)=2y-x,
Profit triple =3(y-x) it is clear,
But,selling price doubled then it should be;
S.P doubled =2y.

Then how come 2y-x?
I could not get it. Please tell me.

We take selling price as -x and cost price- y we assume this! Then given sp is doubled so the profit will be s.p - c. P = 2X-Y.

Also, profit becomes tripled means 3* (x-y).

Therefore equatting 2x-y = 3(x-y) , we get x=2y or y=x/2! Now We know profit = (gain*100)/C P.

Gain is x-y we got y=2y substituting here we get gain= 2y-y=y therefore profit=y*100/y=100.