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?

34%
44%
54%
64%
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 6 of 14.

Naveena said:   9 years ago
Here,

True value = 5/3.
False value = 3/5.

To find the error => error = true value - false value.
=5/3 - 3/5.

Error = 16/15.

To find error % => error%= (error/true value) * 100.
=16/15 / 5/3 *100.

Error% = 64%.

Since, this is the simplification of this problem.

Gabriel said:   9 years ago
Two groups of students went into the shop. The first group bought four hot dogs and six juices and paid N$71.00 the second group bought three hotdogs and seven juices and paid N$67.00 what were the prices for these items (hotdog&juice)?

Can anyone solve this problem?

Triveni said:   9 years ago
@Chris It.

You clear my doubt. Thank you so much.

Satya said:   9 years ago
@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.

Jac said:   9 years ago
This session is very helpful. Thanks.

Ybm said:   9 years ago
The shortcut is (Diff ÷ original number)100.

Raj said:   9 years ago
What is the logic behind the term (16x/15 * 3/5x)?

Rakesh said:   9 years ago
Great answer @Srihari.

MaDX said:   9 years ago
@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%.

Ganesh said:   9 years ago
@Sudershan. Thanks for your solution.


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