Test Index

Ratio and Proportion

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Question : 8 of 112

Marks: +1, -0

The marks obtained by a student in 3 subject

a, b

c

are in the ratio of

\; \frac{1}{2} : \; \frac{1}{3} : \; \frac{3}{5} .

If his total score is 430 then his marks in

c

is

150
100
180
none

Solution:

Concept:

Convert a fractional ratio into a whole number ratio to simplify the calculation of each part.

Explanation:

The given ratio is

\frac{1}{2} : \frac{1}{3} : \frac{3}{5}

.

Find the LCM of the denominators

2

,

3

, and

5

, which is

30

.

Multiply each term by

30

:

\frac{1}{2} \times 30 = 15

,

\frac{1}{3} \times 30 = 10

,

\frac{3}{5} \times 30 = 18

.

Thus, the simplified ratio is

15 : 10 : 18

.

Sum of the parts =

15 + 10 + 18 = 43

.

Total marks =

430

, so each part equals

430 \div 43 = 10

marks.

Marks in subject

c

=

18 \times 10 = 180

.

Answer:

180

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