Aptitude - Percentage - Discussion
Discussion Forum : Percentage - General Questions (Q.No. 9)
9.
| A student multiplied a number by | 3 | instead of | 5 | . |
| 5 | 3 |
What is the percentage error in the calculation?
Answer: Option
Explanation:
Let the number be x.
| Then, error = | 5 | x - | 3 | x = | 16 | x. |
| 3 | 5 | 15 |
| Error% = |  |
16x | x | 3 | x 100 |  % = 64%. |
| 15 | 5x |
Discussion:
134 comments Page 12 of 14.
Manoj Patil said:
4 years ago
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.
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.
(9)
Insaan said:
4 years ago
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%.
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%.
Gokul Ramakrishnan said:
4 years ago
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%.
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%.
(3)
Zubi said:
4 years ago
First of all, we have to know the formulae;
Error = true value - false value.
Error% = error/true value.
Now solution:-
Here, Error = (5/3)-(3/5)=16/15
So, Error% = (error/true value)*100,
= {(16/15)/(5/3)}*100,
= 64%.
Error = true value - false value.
Error% = error/true value.
Now solution:-
Here, Error = (5/3)-(3/5)=16/15
So, Error% = (error/true value)*100,
= {(16/15)/(5/3)}*100,
= 64%.
(57)
Guru said:
4 years ago
Lets take the number is 15.
Correct value is 5/3*15 = 25.
The error value is 3/5 * 15 = 9,
The difference is 11,
So 11/25*10 = 64.
Correct value is 5/3*15 = 25.
The error value is 3/5 * 15 = 9,
The difference is 11,
So 11/25*10 = 64.
(6)
Pooja said:
4 years ago
@Pradip Zala: at last, why we take 100/500. Can you explain?
Venkatesh said:
4 years ago
Thank you @Srihari.
(3)
Helal said:
3 years ago
Let, X be the exact value.
And Y be the error value.
Now, the formula for percentage error= (X-Y)/X *100%
{(5/3-3/5)÷5/3}*100%.
= (16/15*3/5)*100%,
= 64%.
And Y be the error value.
Now, the formula for percentage error= (X-Y)/X *100%
{(5/3-3/5)÷5/3}*100%.
= (16/15*3/5)*100%,
= 64%.
(11)
Tufayel BD said:
3 years ago
Let number is 100.
Actual Multiplication = (100 *5)/3 = 500/3.
Student multiplied = (100 *3)/5 = 300/5.
Error,
= (500/3) - (300/5),
= (2500 - 900)/15,
= 1600/15.
%Error = (1600 *100 *3)/(15*500) = 64%.
Actual Multiplication = (100 *5)/3 = 500/3.
Student multiplied = (100 *3)/5 = 300/5.
Error,
= (500/3) - (300/5),
= (2500 - 900)/15,
= 1600/15.
%Error = (1600 *100 *3)/(15*500) = 64%.
(17)
M.Lokesh said:
3 years ago
Error comes from true value so;.
Error% = error/true value.
Error% = error/true value.
(18)
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