11. Fresh grapes contain 80 % water dry grapes contain 10 % water. If the weight of dry grapes is 250 kg. What was its total weight when it was fresh?
A. 1000 kg
B. 1100 kg
C. 1125 kg
D. 1225 kg
Answer: Option C
Explanation:
Let the weight of fresh grapes be x kg
Quantity of water in it = ([latex]\frac{80}{100}[/latex] × x)kg = [latex]\frac{4x}{5}[/latex] kg
Quantity of pulp in it = (x – [latex]\frac{4x}{5}[/latex])kg = [latex]\frac{x}{5}[/latex] kg
Quantity of water in 250 kg dry grapes
= ([latex]\frac{10 }{100}[/latex] × 250)kg = 25kg
Quantity of pulp in it = (250 - 25)kg = 225 kg
Therefore, [latex]\frac{x}{5}[/latex] = 225
=> x = 1125
12. The quality of water that should be added to reduce 9 ml. Lotion containing 50 % alcohol to a lotion containing 30 % alcohol is
A. 3 ml
B. 4 ml
C. 5 ml
D. 6 ml
Answer: Option D
Explanation:
Alcohol in 9 ml lotion = ([latex]\frac{50 }{100}[/latex] × 9)ml = 4.5ml
Water in it = (9 – 4.5)ml = 4.5ml
Let x ml of water be added to it, then [latex]\frac{4.5}{9+x}[/latex] × 100 = 30
=> [latex]\frac{4.5 }{9+x}[/latex] = [latex]\frac{30 }{100}[/latex] = [latex]\frac{3}{10}[/latex]
=> 3(9+x) = 45 => 27 + 3x = 45
=> 3x = 18
=> x = 6
Water to be added = 6 ml
13. In two successive years, 100 and 75 students of a school appeared at the final examination. Respectively 75 % and 60 % of them passed. The average rate of pass is:
A. 68 [latex]\frac{4}{7}[/latex] %
B. 78 %
C. 80 %
D. 80 [latex]\frac{4}{7}[/latex] %
Answer: Option A
Explanation:
Total candidates = (100 + 75) = 175
Total passed = ([latex]\frac{75}{100}[/latex] × 100) + ([latex]\frac{60}{100}[/latex] × 75)
= (75 + 45) = 120
Therefore Pass % = ([latex]\frac{120}{175}[/latex] × 100)%
= 480/7 % = 68 4/7 %
14. Of the 1000 inhabitants of a town 60 % are males of whom 20 % are literate. If of all the inhabitants 25 % are literate. Then what percent of the females of the town are literate?
A. 22. 5 %
B. 27.5 %
C. 32. 5 %
D. 37.5 %
Answer: Option C
Explanation:
Males = (60/100 × 1000) = 600,
females = (1000 - 600) = 400
Literate males = ([latex]\frac{20 }{100}[/latex] × 600) = 120
Total literates = ([latex]\frac{25 }{100}[/latex] × 1000) = 250
Female literates = (250 - 120) = 130
Required % = ( [latex]\frac{130}{140}[/latex] × 100)% = 32.5 %
15. In a school, 40 % of the students play football and 50 % play cricket. If 18 % of the students play neither football nor cricket, the percentage of students playing both is
A. 40 %
B. 32 %
C. 22 %
D. 8 %
Answer: Option A
Explanation:
Let A = set of students who play football and
B = set of students play cricket.
Then n(A) = 40, n (B) = 50 and
n(A U B) = (100 - 18) = 82
n(A U B) = n(A) + n(B) – n(A ∩ B)
n(A∩B) = n(A) + n(B) – n(AUB) = (40 + 50 -82) = 8
Percentage of the students who play both = 8%