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Percentage - Aptitude MCQ Questions and Solutions with Explanations

Percentage MCQ Questions and answers with easy and logical explanations.Arithmetic Ability provides you all type of quantitative and competitive aptitude mcq questions on Percentage with easy and logical explanations. Percentage MCQ is important for exams like Banking exams,IBPS,SCC,CAT,XAT,MAT etc. Page-3 section-5

Each section contains 100 MCQs on Percentage .
21
In a factory, producing parts for an automobile, the parts manufactured on the shop floor are required to go through three quality checks, each conducted after a specific part of the processing on the raw materials is completed. Only parts that are not rejected at one stage are put through the subsequent stages of production and testing. If average rejection rates at these testing machines during a month are 10%, 5% and 2% respectively, then what is the effective rejection rate for the whole plant ?
Discuss
Answer & Solution
Answer: Option B
Solution:
Let the number of parts before the quality checks be 100
Then, number of parts passed after quality checks
= (100 - 2)% of (100 - 5)% of (100 - 10)% of 100
= 98% of 95 of 90% of 100
= $$\left( {\frac{{98}}{{100}} \times \frac{{95}}{{100}} \times \frac{{90}}{{100}} \times 100} \right)$$
= $$\left( {\frac{{8379}}{{100}}} \right)$$
= 83.79
∴ Effective rejection rate :
= (100 - 83.79)%
= 16.21%
22
Depreciation applicable to an equipment is 20%. The value of the equipment 3 years from now will be less by :
Discuss
Answer & Solution
Answer: Option B
Solution:
Let the present value be Rs. 100
Value after 3 years :
$$\eqalign{ & = {\text{Rs}}{\text{. }}\left[ {100 \times {{\left( {1 - \frac{{20}}{{100}}} \right)}^3}} \right] \cr & = {\text{Rs}}{\text{. }}\left( {100 \times \frac{4}{5} \times \frac{4}{5} \times \frac{4}{5}} \right) \cr & = {\text{Rs}}{\text{. 51}}{\text{.20}} \cr} $$
∴ Reduction in value :
= (100 - 51.20)%
= 48.8%
23
In a hotel, 60% had vegetarian lunch while 30% had non-vegetarian lunch and 15% had both types of lunch. If 96 people were present, how many did not eat either type of lunch ?
Discuss
Answer & Solution
Answer: Option B
Solution:
$$\eqalign{ & n\left( A \right) = \left( {\frac{{60}}{{100}} \times 96} \right) = \frac{{288}}{5} \cr & n\left( B \right) = \left( {\frac{{30}}{{100}} \times 96} \right) = \frac{{144}}{5} \cr & n\left( {A \cap B} \right) = \left( {\frac{{15}}{{100}} \times 96} \right) = \frac{{72}}{5} \cr & \therefore n\left( {A \cup B} \right): \cr & = n\left( A \right) + n\left( B \right) - n\left( {A \cap B} \right) \cr & = \frac{{288}}{5} + \frac{{144}}{5} - \frac{{72}}{5} \cr & = \frac{{360}}{5} \cr & = 72 \cr} $$
So, people who had either or both types of lunch = 72
Hence, people who had neither type of lunch = (96 - 72) = 24
24
1 litre of water is added to 5 litres of alcohol water solution containing 40% alcohol strength. The strength of alcohol in the new solution will be :
Discuss
Answer & Solution
Answer: Option B
Solution:
Quantity of alcohol :
= $$\left( {\frac{{40}}{{100}} \times 5} \right)$$   litres
= 2 litres
∴ New strength :
$$\eqalign{ & = \left( {\frac{2}{6} \times 100} \right)\% \cr & = 33\frac{1}{3}\% \cr} $$
25
Solve this : 30% of 1225 - 64% of 555 = ?
Discuss
Answer & Solution
Answer: Option B
Solution:
Given,
30% of 1225 - 64% of 555 = (?)
$$\eqalign{ & = \left( {\frac{{30}}{{100}} \times 1225} \right) - \left( {\frac{{64}}{{100}} \times 555} \right) \cr & = \left( {367.5 - 355.2} \right) \cr & = 12.3 \cr} $$
26
One litre of water is evaporated from a 6 litre solution containing 4% sugar. The percentage of sugar in the remaining solution is :
Discuss
Answer & Solution
Answer: Option C
Solution:
Quantity of sugar
$$\eqalign{ & = \left( {\frac{4}{{100}} \times 6} \right)kg \cr & = 0.24\,\,kg \cr} $$
∴ New percentage :
$$\eqalign{ & = \left( {\frac{{0.24}}{5} \times 100} \right)\% \cr & = 4\frac{4}{5}\% \cr} $$
27
Find the number :
85% of 420 + ?% of 1080 = 735
Discuss
Answer & Solution
Answer: Option C
Solution:
Given,
(85% of 420) + (?% of 1080) = 735
$$ \Rightarrow \left( {\frac{{85 \times 420}}{{100}}} \right) \times \left( {\frac{{(?) \times 1080}}{{40}}} \right)$$       $$= 735$$
$$\eqalign{ & \Rightarrow 357 + \left( {\frac{{(?) \times 1080}}{{100}}} \right) = 735 \cr & \Rightarrow \left( {\frac{{(?) \times 1080}}{{100}}} \right) = \left( {735 - 357} \right) \cr & \Rightarrow \left( {\frac{{(?) \times 1080}}{{100}}} \right) = 378 \cr & \Rightarrow (?) = \frac{{378 \times 100}}{{1080}} \cr & \Rightarrow (?) = 35 \cr} $$
28
What is 45% of 25% of $$\frac{4}{5}$$th of 850 ?
Discuss
Answer & Solution
Answer: Option C
Solution:
Given expression :
$$\eqalign{ & = \left( {\frac{{45}}{{100}} \times \frac{{25}}{{100}} \times \frac{4}{5} \times 850} \right) \cr & = \frac{{153}}{2} \cr & = 76.5 \cr} $$
29
In an examination it is required to get 36% of the aggregate marks to pass. A student gets 198 marks and is declared failed by 36 marks. What is the maximum aggregate marks a student can get ?
Discuss
Answer & Solution
Answer: Option C
Solution:
Let the maximum marks be x
Then,
36% of x = 198 + 36
⇒ $$\frac{36x}{100}$$ = 234
⇒ x = $$\frac{234 × 100}{36}$$
⇒ x = 650
30
It costs Rs. 1 to photocopy a sheet of paper. However, 2% discount is allowed on all photocopies done after first 1000 sheets. How much will it cost to copy 5000 sheets of paper ?
Discuss
Answer & Solution
Answer: Option D
Solution:
Total cost :
= Rs. [1 × 1000 + (100 - 2)% of 1 × 4000]
= Rs. (1000 + 0.98 × 4000)
= Rs. (1000 + 3920)
= Rs. 4920