Tips and Tricks of The Day


Record Limit : 

    2019-Oct-18
Ex: A vessel contains a mixture of milk and water in the respective ratio of 14 : 3. 25. When 22 litre water is added new ratio of milk and water becomes 7:3. Find initial quantity of mixture. (in liter)
(A) 125 
(B) 138 
(C) 136 
(D) 148 
Trick:
Before      56:13
After         56:24
Now (24-13) = 11 = 22 liter
So 1 = 2 liter
Required answer=(56+13)×2 = 138 liter
    2019-Oct-17
Ex: An amount is to be distributed among four workers P, Q, R, and S in the proportion of 7 : 4 : 5 : 2. If Q gets Rs. 800 more than S, what is P's share?
A. 2500
B. 2800
C. 2600
D. 2200
Trick: 
Let P's, Q's , R's and S's share be 7x, 4x, 5x, and 2x respectively.
4x = 2x + 800
x = 400
So, P's share is 7 * 400 = Rs. 2800
    2019-Oct-16
Ex: 700 ml of a mixture contains water and milk in the ratio 2:8. How much water must be added to the mixture so that the ratio of water and milk becomes 3:8?
A. 75 ml
B. 65 ml
C. 70 ml
D. 60 ml
Trick:
Milk in the 700 ml of mixture = 700 ∗ 8/10 =560ml
So, water in the mixture would be = 700 - 560 = 140 ml
Let water to be added = x ml
Now, 140+x / 560 = 3 / 8
1120+8x = 1680
8x = 1680 - 1120
8x= 560
x = 560/8 = 70 ml
    2019-Oct-15
Ex: Sulabh, Sudheer and Satyam hired a field for Rs.800 for the whole year. Sulabh puts in 50 cows for 2 months, Sudheer 80 cows for 5 months and Satyam 60 cows and 30 calves for 4 months. How much should Satyam pay if one cow eats as much as 2 calves?
(A) Rs.100
(B) Rs.250
(C) Rs.300
(D) Rs.400
Trick:
 30 calves = 1/2 × 30 = 15 cows
60 cows + 30 calves= (60+15) 
= 75 cows
Ratio in the number of their cows
= 50 × 2 : 80 × 5 : 75 × 4 
= 100 : 400 : 300
= 1 : 4 : 3
Share of Satyam in rent = 3 * 800 / 8 = Rs.300 
    2019-Oct-11
Ex: In a shower 10 cm of rain falls. What is the volume of water that falls on 1.5 hectares of ground?
A. 1500 m3
B. 1400 m3
C. 1200 m3
D. 1000 m3
Trick:
1 hectare = 10,000 m2
1.5 hectare = 1.5 x 10 x 1000 = 15,000 m2
Depth = 10 cm of rainfall = 10/100
∴ Volume of water = Area * Depth 
15,000 * 10/100 = 1500 m3
    2019-Oct-10
Ex: A sum of money amounts to 3300 in 2 years and Rs. 3600 in 5 years. What is the principal amount?
A. Rs. 2700
B. Rs. 2850
C. Rs. 2950
D. Rs. 3100
Trick:
After two years the amount is Rs. 3300 and in the next three years it becomes Rs. 3600.
Therefore, S.I for three years = 3600 -3300 = 300
S.I for one year = 300/( 3 ) = 100
S.I for two years = 100 * 2 = 200
Principal = 3300 - 200 = Rs. 3100
    2019-Oct-09
Ex: The ratio of population of two towns A and B was 6 : 7 last year. This year, the population of A is incereased by 20% and that of B by 40,000. If their population are now in the ratio of 24 : 25, the population of A was-
(A) 560000 
(B) 480000 
(C) 600000 
(D) 576000 
Trick:
Let the population of A and B be 6x and 7x respectively.
6x + 20% of 6x / 7x + 40000 = 24/25
150x + 30x = 168x + 960000
12x = 960000
12x = 80000 
x = 80000
Population of A was 6 × 80000
= 480000
    2019-Oct-07
Ex: M borrowed a sum of Rs.1150 from A at the simple rate of 6 p.c.p.a. for 3 years. He then added some more money to the borrowed sum and lent it to S for the same time at 9 p.c.p.a. at simple interest. If M gains Rs.274.95 from the whole transaction, then what is the sum lent by him to S?
A. Rs.1820 
B. Rs.1758 
C. Rs.1785 
D. Rs.1930 
Trick:
(9 × 3)% of (1150+ x) - (6 × 3)% of 1150 
= 274.95
9% of 1150 + 27% of x = 274.95
x = Rs.635
Sum lent to S = Rs.1150 + Rs.635 = Rs.1785
    2019-Oct-04
Ex: A man rows downstream at 20 km/hr and rows upstream at 15 km/hr. At what speed he can row in still water?
A. 17.5 km/hr
B. 18 km/hr
C. 20.5 km/hr
D. 22 km/hr
Trick:
Speed in still water = 1/2(speed downstream + speed upstream)
Speed downstream = 20 km/hr
Speed upstream = 15 km/hr
∴ Required speed = 1/2 (20 + 15) km/hr
= 1/2 ∗ 35 = 17.5 km/hr
    2019-Oct-03
Ex: The ratio of milk and water in a mixture of 45 litre is 4: 1. If 3 litre more water should be added then what will be the new ratio of milk and water?
(A) 22.5% 
(B) 25% 
(C) 33.33% 
(D) 30% 
Trick:
Milk : water = 1: 4 
Sum of ratios = 1 + 4 = 5
Quantity of water in 45 litres of mixture = 45 × (1/5) = 9 litre
Quantity of milk in 45 litres of mixture = 45 × (4/5) = 36 litre
If 3 litre of water be added then new ratio becomes 
= (9+3) : 36
= 12: 36
= 1: 3