1. In an army selection process, the ratio of selected to unselected was 6:1. If 90 less had applied and 30 less selected, the ratio of selected to unselected would have been 8:1. How many candidates had applied for the process?
A. 3150
B. 6300
C. 4725
D. 1575
Answer - Option
Explanation -
Let the number of selected and unselected candidates be 6x and x respectively.
Then, number of candidates applied = 6x + x = 7x
According to the question,
If 90 less applied and 30 less selected, the ratio of selected to unselected candidates = [latex]\frac {8}{1}[/latex], i.e.
New number of selected candidates = 6x – 30
And new number of applied candidates = 7x – 90
∴new number of candidate unselected = 7x – 90 – (6x – 30)
= x – 60
Thus, [latex]\frac {6x - 30}{x - 60} = \frac {8}{1}[/latex]
[latex]\Rightarrow[/latex] 6x – 30 = 8x – 480
[latex]\Rightarrow[/latex] x = 225
Thus, the number of candidates applied for the process = 7x
= 7 × 225
= 1575
2. The price of gold is directly proportional to square of its weight. A person broke down the gold 3:2:1 and face a loss of Rs 4,620. Find the initial price of gold.
A. 7560
B. 6560
C. 7450
D. 7440
Answer - Option A
Explanation -
3:2:1 [latex]\rightarrow[/latex] 6 (According to Question) [latex]\rightarrow[/latex] 36 (On squaring)
In this question if we brake it in the ratio and then squaring it then we get 14 (9 + 4 + 1)
So, we loss 22 (36 - 14) if we broke it
Loss = Rs. 4620
Initial price = [latex]\frac {4620}{22} \times 36[/latex]
= Rs 7560
3. The no. of mangoes on three baskets are in the ratio of 3 : 5 : 7. In which ratio the no. of mangoes in first two baskets must be increase so that the new ratio becomes 5 : 6 : 8.
A. 3 : 13
B. 12 : 7
C. 11 : 2
D. 13 : 3
Answer - Option C
Explanation -
A.T.Q.
[latex]{B}_{1} : {B}_{2} : {B}_{3} = 3X : 5X : 7X[/latex]
and again,
[latex]{B}_{1} : {B}_{2} : {B}_{3} = 5X : 6X : 8X[/latex]
According to question there is increase in first two baskets only. It means the no. of mangoes remain constant in the third basket.
So, 7x = 8y or x = [latex]\frac {8}{7} y[/latex] Hence, 3x : 5x : 7x = [latex]3 \times \frac {8}{7} y : 5 \times \frac {8}{7} y : 7 \times \frac {8}{7} y [/latex]
= 24y : 40y : 56y and 5y : 6y : 8y [latex]\Rightarrow[/latex] 35y : 42y: 56y
i.e, increase in first basket = 11 increases in second basket = 2 Required ratio = 11 : 2
4. In a mixture of 60 liters, the ratio of milk and water 2:1. If this ratio is to be 1:2 , then the quantity of water to be further added is:
A. 20 liters
B. 30 liters
C. 40 liters
D. 60 liters
Answer - Option D
Explanation -
Quantity of milk =[latex]60 \times \frac {2}{3}[/latex] = 40 liters
Quantity of water = 60 - 40 = 20 liters
Let x liters of water to be added so as to get the ratio 1:2. Then,
[latex]\frac {40}{20 + x} = \frac {1}{2}[/latex]
x = 80 - 20 = 60 liters
5. Two numbers are in the ratio 3: 5. If 9 is subtracted from each number, then they are in the ratio of 12: 23. What is the second number?
Answer - Option B
Explanation -
Let the numbers be 3x & 5x (since they are in the ratio of 3:5)
So, subtraction 9, we get
3x - 9 and 5x - 9
Now, the ratio is 12 :12: (given)
[latex]\frac {3x - 9}{5x - 9} = \frac {12}{23}[/latex]
(By cross multiplication)
23(3x - 9) = 12(5x -9)
69x - 207 = 60x - 108
9x = 99
x = 11
So, the original numbers are 3x = 3 [latex]\times[/latex] 11 = 33 and 5 [latex]\times[/latex] 11 = 55 , with the second number being 5.