Aptitude - Percentage - Discussion

Here, I use ratio and proportion. The question states using a number of some value and multiplying by 3/5 and 5/3. what is the difference in percentage?

3/5 = 60%. 5/3 = 166.6%.
The percentage difference is arguably 107%. If you use a predetermined value of 10.
The equations are 3/5 x 10 = .6 and 5/3 x 10 = 1.66. The calculated % is 1.66/.6 = 2.76 or 276%.
This is the true difference in % values no matter what number you multiply them by. 276% x 0.6 = 1.66.

Hey take suppose a number 10 and multiply with 3/5 i.e >3/5*10=6, and the same number 10 is multiplied by 5/3.

i.e >5/3*10=16. 6=~17 then get the difference from each 17-6=11 then to find the real value and fake value.

Real value =17 anf the fake value =6.

So, we have the task to find the difference values percentage over the real value i.e >17 is 100% then 11 (difference value) is what percentage of 17 =64%.

In this question, take LCM of denominators of fractions 3/5 & 5/3 ( to make the calculation easier).

As the denominators are 5 & 3,
LCM is 15.

Now
Mistaken value = 15 * (3/5) = 9,
True value = 15 * (5/3)= 25.

Error = ( True value - mistaken value )/( true value),
= (25 - 9)/ 25 = 16/25,

Error %= Error * 100.
= (16/25)* 100.
= 64%.

Hope this helps.

@Gabriel.

We need to write the statement in the form of equations:
The price of
4 hd + 6 ju =71--> (1)
3 hd + 7 ju =67--> (2)

Multiply 3 & 4 with eq.(1) and (2) respectively.(aim is to make equal Coeff. of hd) then new equation will be;
12 hd + 18 ju = 213--> (3)
12 hd + 28 ju = 268--> (4)

Subtract eq (3) from eq.(4)
Answer is
Juice = $5.5.
Hot dogs = $9.5.

A Person has multiplied a number by 3/5 instead of 5/3.
For simplicity consider the number as 15.
15*(3/5)=9 and 15*(5/3)=25.
the person should have got ans as 25 but because of his mistake, he got 9.
Error is 25-9=16 convert to percentage
if 25 is 100%
16--->?

(16*100)/25= 64%.

Here I considered the number to be 15 since it easily divides by the denominator.

We have to find error %.
percentage calculate from original value. So to find error percent

1.First v have to find the error.
2.Then percentage for error in original.

error = Original value - Wrong value.
= (5/3 x) - (3/5 x).
= 16/15 x

error% = error/original * 100;
= ((16/15 x) / (5/3 x)) * 100
= 64

So 64%

@Raj, We have to find error %.
And like S.P and C.P, the percentage are calculated from the original value.

1.First we have to find the error:

Error = Original value - Wrong value.
= (5/3 x) - (3/5 x).
= 16/15x.

2.Then percentage for error in original.
error% = error/original * 100;
= (16/15 x)/(5/3 x) * 100.
= 64%.

So 64%.

LET Number = 1.

Correct number = 5/3.
Incorrect number = 3/5.

We know that:

%error = (true value- false value)100/(true value).

%error = (5/3-3/5)100/(5/3).

Solve it and you got 64%.

Tips: When ever you got this type of question always choose 1 as no. It make your calculation easier and simplest.

Thanks.

Error% = Error/True value.

But we have to calculate error value first.

So, Error = True value-False value.

Here, T.V = 5/3 & F.V = 3/5.

= 5/3-3/5, by solving this we get.

Error = 16/15.

Now, to calculate error%,

Error % = 16/15/5/3*100.

= 16/15*3/5*100 = 16/5*20.

= 64%.

To find error = true value - false value.
So, 5/3 - 3/5 ( to subtract we need to make denominator same) ( here multiply 3*5= 15)
5*5/3*5 - 3*3/5*3 = 25/15 - 9/15,
= 16/15.

To now find error %
Take the 16/15 *3/5 *100( taking 100 bcos its in percentage),
48/75 *100,
64%.