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 5 of 14.
Subham said:
1 decade ago
= (3/5-5/3)*(5/3)*100.
Sam said:
10 years ago
Let the no is 15, then.
3/5*15 = 9.
5/3*15 = 25.
The difference of both is 16.
Then the error percentage is:
Error% = (25-9)/25*100 = 64%.
3/5*15 = 9.
5/3*15 = 25.
The difference of both is 16.
Then the error percentage is:
Error% = (25-9)/25*100 = 64%.
Suchita said:
10 years ago
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%.
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%.
Harshit Garg said:
10 years ago
Why error% can't be = error/incorrect value?
Secilia said:
9 years ago
Still I did not get how you come up with 16/15. Maybe you can explain more.
Toini N Mutota said:
9 years ago
I still didn't get it, how did you get the answer.
Anusha said:
9 years ago
I can't understand these problems. Is there any trick to solve the solution?
Michael said:
9 years ago
Let the number be x.
Multiply by 3/5 = 3x/5 which is false.
True value 5/3 * x = 5x/3.
%error = [(true value - false value)/true value] * 100%.
= [(5x/3 - 3x/5)/(5x/3) ] * 100.
= [(16x/15)/(5x/3)] 100%.
= 16/25 * 100%.
= 64%.
Multiply by 3/5 = 3x/5 which is false.
True value 5/3 * x = 5x/3.
%error = [(true value - false value)/true value] * 100%.
= [(5x/3 - 3x/5)/(5x/3) ] * 100.
= [(16x/15)/(5x/3)] 100%.
= 16/25 * 100%.
= 64%.
Vengamanaidu said:
9 years ago
Thank you @Michael, your explanation is the best method.
Vipin said:
9 years ago
It's simple,
1. Let number be x
2. Error = true value - false value
3. 5/3 x - 3/5 = 16/15 x
4. We know the formula -> change = difference / initial value * 100
So, 16/15 x / 5/3 x *100 = 64 % -----> percentage we right because in question we say that error %.
1. Let number be x
2. Error = true value - false value
3. 5/3 x - 3/5 = 16/15 x
4. We know the formula -> change = difference / initial value * 100
So, 16/15 x / 5/3 x *100 = 64 % -----> percentage we right because in question we say that error %.
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