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71
A monthly return railway ticket cost 25 percent more than a single ticket. A week's extension can be had for the former by paying 5 percent of the monthly ticket's cost. If the money paid for the monthly ticket (with extension) is Rs. 84, the price of the single ticket is :
Discuss
Answer & Solution
Answer: Option B
Solution:
Let the cost of a single ticket be Rs. $$x$$
The, cost of monthly return ticket :
$$\eqalign{ & = 125\% \,\,{\text{of}}\,\,{\text{Rs}}.x \cr & = {\text{Rs}}{\text{. }}\left( {\frac{{125}}{{100}}x} \right) \cr & = {\text{Rs}}{\text{. }}\frac{{5x}}{4} \cr} $$
Cost of monthly return ticket with extension :
$$\eqalign{ & = 105\% \,\,{\text{of}}\,\,{\text{Rs}}.\frac{{5x}}{4} \cr & = {\text{Rs}}{\text{. }}\left( {\frac{{105}}{{100}} \times \frac{{5x}}{4}} \right) \cr & = {\text{Rs}}{\text{. }}\frac{{21x}}{{16}} \cr} $$
$$\eqalign{ & \therefore \frac{{21x}}{{16}} = 84 \cr & \Rightarrow x = \left( {\frac{{84 \times 16}}{{21}}} \right) \cr & \Rightarrow x = 64 \cr} $$
72
Fresh grapes contain 80 percent water while dry grapes contain 10 percent water. If the weight of dry grapes is 250 kg what was its total weight when it was fresh ?
Discuss
Answer & Solution
Answer: Option C
Solution:
Quantity of pulp in fresh grapes = Quantity of pulp in dry grapes
= (100 - 10)% of 250 kg
= 90% of 250 kg
= 225 kg
Let the total weight of fresh grapes be $$x$$ kg
Then,
⇒ (100 - 80)% of $$x$$ = 225
⇒ 20% of $$x$$ = 225
⇒ $$\frac{x}{5}$$ = 225
⇒ $$x$$ = 225 × 5
⇒ $$x$$ = 1125
Hence, total weight of fresh grapes = 1125 kg
73
When income tax is 3 paise in a rupee, a person's net income is Rs. 237650. What will it be when the income tax is raised to 7 paise ?
Discuss
Answer & Solution
Answer: Option C
Solution:
Let the person's gross income be Rs. $$x$$
Then,
⇒ (100 - 3)% of $$x$$ = 237650
⇒ 97% of $$x$$ = 237650
⇒ $$\frac{97x}{100}$$ = 237650
⇒ $$x$$ = $$\left( {\frac{{237650 \times 100}}{{97}}} \right)$$
⇒ $$x$$ = 245000
∴ When income tax is raised to 7%, we have :
Net income :
= (100 - 7)% of Rs. 245000
= 93% of Rs. 245000
= Rs. $$\left( {\frac{{93}}{{100}} \times 245000} \right)$$
= Rs. 227850
74
In a certain month a base ball team that played 60 games had won 30% of its games played. After a phenomenal winning streak this team raised its average to 50%. How many games must the team have won in a row to attain this average ?
Discuss
Answer & Solution
Answer: Option C
Solution:
Number of games already won
= 30% of 60
= 18
Let the required number of games be $$x$$
Then,
$$\eqalign{ & \Rightarrow \frac{{18 + x}}{{60 + x}} \times 100 = 50 \cr & \Rightarrow \frac{{18 + x}}{{60 + x}} = \frac{1}{2} \cr & \Rightarrow 36 + 2x = 60 + x \cr & \Rightarrow x = 24 \cr} $$
75
The numbers are respectively $$12\frac{1}{2}\% $$  and $$25\% $$ more than a third number. The as a percentage of the second number is :
Discuss
Answer & Solution
Answer: Option D
Solution:
Let the third number be $$x$$
Then, first number :
= $$112\frac{1}{2}\% $$  of $$x$$
= $$\frac{9x}{8}$$
Second number :
= 125% of $$x$$
= $$\frac{5x}{4}$$
∴ Required percentage :
= $$\left( {\frac{{9x}}{8} \times \frac{{4}}{{5x}} \times 100} \right)$$   %
= 90%
76
Two successive price increases of 10% each on an article are equivalent to a single price increase of :
Discuss
Answer & Solution
Answer: Option C
Solution:
Let the original price be Rs. $$x$$
New final price :
= 110% of (110% of Rs. 100)
= Rs. $$\left( {\frac{{110}}{{100}} \times \frac{{110}}{{100}} \times 100} \right)$$
= Rs. 121
∴ Total increase :
= (121 - 100)%
= 21%
77
In a market research project, 20% opted for Nirma detergent whereas 60% opted for Surf Blue detergent. The remaining individuals were not certain. If the difference between those who opted for Surf Blue and those who were uncertain was 720, how many respondents were covered in the survey ?
Discuss
Answer & Solution
Answer: Option B
Solution:
Let the total number of respondents be $$x$$
Percentage of uncertain individuals :
= [100 - (20 + 60)]%
= 20%
∴ 60% of $$x$$ - 20% of $$x$$ = 720
⇒ 40% of $$x$$ = 720
⇒ $$\frac{{40x}}{{100}}$$ = 720
⇒ $$x$$ = $$\left( {\frac{{720 \times 100}}{{40}}} \right)$$
⇒ $$x$$ = 1800
78
In an examination, 5% of the applicants were found ineligible and 85% of the eligible candidates belonged to the general category. If 4275 eligible candidates belonged to other categories, then how many candidates applied for the examinations ?
Discuss
Answer & Solution
Answer: Option A
Solution:
Let the total number of applicants be $$x$$
Number of eligible candidates = 95 % of $$x$$
Eligible candidates of other categories
= 15% of (95 of $$x$$)
= $$\left( {\frac{{15}}{{100}} \times \frac{{95}}{{100}} \times x} \right)$$
= $$\frac{{57x}}{{400}}$$
∴ $$\frac{{57x}}{{400}}$$ = 4275
⇒ $$x$$ = $$\left( {\frac{{4275 \times 400}}{{57}}} \right)$$
⇒ $$x$$ = 30000
79
the price of sugar increases by 32%. A family reduces its consumption so that the expenditure of the sugar is up only by 10%. If the total consumption of the sugar before the price rise was 10 kg per month, then the consumption of sugar per month at present (in kg) is :
Discuss
Answer & Solution
Answer: Option A
Solution:
Let the original price of sugar be Rs. 10 per kg
Then, original expenditure = Rs. (10 × 10) = Rs. 100
New expenditure = 110% of Rs. 100 = Rs. 110
New price of sugar = 132% of Rs. 10 = Rs. 13.20
New consumption :
= $$\frac{110}{13.20}$$ kg
= $$\frac{25}{3}$$ kg
= $$8\frac{1}{3}$$ kg
80
On a test consisting of 250 questions, Jassi answered 40% of the first 125 questions correctly. What percent of the other 125 questions does she need to answer correctly for her grade on the entire exam to be 60% ?
Discuss
Answer & Solution
Answer: Option C
Solution:
Number of questions answered correctly :
= 40% of 125
= 50
For 60% grade, number of questions to be answered correctly :
= 60% of 250
= 150
Remaining number of question to be answered correctly :
= 150 - 50
= 100
∴ Required percentage :
= $$\left( {\frac{{100}}{{125}} \times 100} \right)\% $$
= 80%