SBI Clerk 2019 Prelims: Quant Test Day 7

Answer: 4. 100/9 days
Explanation:
Given, the ratio of work done by A to B is 2:3.
Let the work done by A per day = 4p
Work done by B per day = 125% of 4p = 5p
Work done by B in x days = 5p*x
Work done by A in x+7 days = 4p*(x+7)
According to question,
4p*(x+7)/5p*x = 3/2
x = 8
work done by B = 5p*8 = 40p , work done by A = (3/2)*40 = 60p
Total work = 40p+60p = 100p
Combined efficiency of A and B = 4p+5p = 9p
Time taken = 100p/9p = 100/9 days

Answer: 1. 42
Explanation:
Let the speed of current is “c”
Downstream speed = 12+c and upstream speed =12-c
According to question,
12+c – (12-c) = 4
C =2
Also,
X/ (12+c) = (X-12)/(12-c)
X/14 = (X-12)/10
10X = 14X-14*12
X= 42 km

Answer: 5) 136 litres
Explanation:
Let the total quantity = 17x
Quantity of milk = 14x and quantity of water = 3x
when 51 liters is taken out, 51*(14/17) = 42 will be milk and 51*(3/17) = 9 will be water
According to question,
(14x-42) / (3x-9+15) = 7/3
(14x-42) / (3x+6) = 7/3
(14x-42) / (x+2) = 7/1
14x-42 = 7x+14
x =8
Mixture quantity in original = 17*8 = 136 liters

Answer: 3) 210m
Explanation:
Let the speed of train is “s”
Distance = Speed*time
280 = s*20
s = 14m/s
Let the length of platform = x
(x+280) = 14*35
X = 210

Answer: 2) 90/19 hours
Explanation:
Let the capacity of tank is LCM of 6, 15 and 45 = 90k
Tank filled per hour by A = 90/6 = 15k
Tank filled per hour by B = 90/15 =6k
Tank emptied per hour by C = 90/45 = 2k
Tank filled per hour by all three taps = 15k+6k-2k = 19k
Time taken by all to fill the tank = 90/19 hours

Answer: 1) 16.66%
Explanation:
Age of x = 120% of age of y
48 = 120% of y
y = (48*100)/120 = 40
Required %age = (48-40)/48 = 8/48 = 1/6 (16.66%)

Answer: Rs. 3900
Explanation:
Let the cost price of the commodity = 100x
Selling price = 130% of 100x = 130x
130x = 4303
X =33.1
100x = 3310
CP = 85% of MP
3310 = 85/100 * MP
MP = 331000/85 =Rs. 3900

Answer: 4. 240
Explanation:
Let the number of boys failed = x, no. of girls failed = x
Number of boys passed = (240-x) and number of girls passed = (220-x)
According to question,
(240-x) = 1.2(220-x)
240-x = 264 – 1.2x
X = 120
Total number of boys and girls failed = x+x = 120+120 = 240

Answer: 3. 4/85
Explanation:
Cards which are divisible by 5 from number 1 to 35 are 7
Cards which are divisible by 8 from number 1 to 35 are 4
If first card is divisible by 8 and second by 5,
Probability of first card being divisible by 8 = 4/35
Probability of second card being divisible = 7/34 (without replacement)
Probability =(4/35)*(7/34) = 2/85
If first card is divisible by 5 and second card is divisible by 8,
Probability of first card being divisible by 5 = 7/35
Probability of second card being divisible by 8 = 4/34(without replacement)
Probability =(7/35)*(4/34) = 2/85
Total Probability = 2/85+2/85 = 4/85

Answer: 1) 10 minutes
Explanation:
Given, the ratio of speed of A and B= 3:5, Ratio of time taken will be 5:3, Difference of time is (5-3)= 2, (here 2 = 12minutes)
Therefore, 1 =6 minutes
Therefore, time taken by A to complete the distance = 5*6 = 30 minutes
Hence, A will cover the same distance with thrice its speed in 10 minutes