Tips and Tricks of The Day


Record Limit : 

    2020-Sep-21
Ex: A boat goes 60 km downstream in 6 hours to reach the destination. The boat will take total 21 hour if it has to go back to the starting point and come back to the destination. Find the speed of boat in still water? (in km/hr)
Trick:
21-6 = 15 hr
U = 60/15 = 4 km/hr
D = 60/ 6 = 10 km/hr
B = (10+4)/2 = 7 km/hr
    2020-Sep-18
Ex: Two equal glasses are respectively 1/4th and 3/5th full of milk. They are then filled up with water and the contents are mixed in another glass. Find the ratio of milk and water in another glass. 
Trick:
M: W
(1: 3)×5 = 5: 15
(3: 2)×4 = 12: 8
17: 23 
    2020-Sep-16
Ex: Dipika found that she had made a loss of 10% while selling his smartphone. She also found that had she sold it for Rs.50 more, she would have made a profit of 5%. The initial loss was what percentage of the profit earned, had she sold the smartphone for a 5% profit ?
Trick:
Profit= 5%
5% of CP = Rs.50
CP = Rs.1000
Now, Loss% = 10%
Loss = Rs.100
Required % = 100/50 * 100 = 200%
    2020-Sep-14
Ex: In how many ways can the word 'EQUATION' be arranged so that vowels are always together?
Trick:
Total number of ways = 6!3!
= 720 × 6 = 4320
    2020-Sep-10
Ex: A work twice as that of B and thrice as that of C.If B and C working together completes a work in 15 days, then A working alone will complete the whole work in how many days?
Trick:
ratio of their work efficiency
A : B : C
6 : 3 : 2
A alone =  15*5 / 6 = 12.5 days
    2020-Sep-09
Ex: A starts a business with Rs 3750.After sometime B joins the business with Rs.15000. When did B join if the total profit is equally divided between them at the end of the year?
Trick:
A:B
12×3750 = x×15000
x = 3 months
B joined the business after 9 months.
    2020-Sep-08
Ex: Water flows into a tank which is 200 m long and 150 m wide, through a pipe of cross-section (0.3m x 0.2m) at 20 km/h. In what time will the water level be 8m?
Trick:
Volume of water collected in the tank in 11 hour
⇒ 0.3×0.2×20×1000=1200 m cubic 
If after t hours, the water is at height of 8m, 
1200t=200×150×8
⇒ t = 200 Hours.
    2020-Sep-07
Ex: X purchased an item at a discount of 10% and sold it to Y at 10% profit. The marked price and the price for which Y purchased the item are in ratio.
(A) 99 : 100
(B) 100 : 99
(C) 101 : 100
(D) 100 : 101
Trick:
M.P = 100
C.P = 100 * 90/100 * 110 / 100 = 99
Ratio = 100 : 99
    2020-Sep-04
Ex: Aanya is two years older than Vibhu who is twice as old as Anu. If the total of the ages of Aanya, Vibhu and Anu be 27, the how old is Vibhu?
(A) 5 years
(B) 7 years
(C) 10 years
(D) 12 years
Trick:
Let Anu is x years old then age of Vibhu and Aanya is 2x and 2x+2 years respectively.
2x + 2x + 2 + x = 27
x = 5 , Hence age of Vibhu = 2 x 5 = 10 years
    2020-Sep-01
Ex: Harsha takes 3 hours more than Bharat, who drives his car 5 km/h faster than Harsha drives, to cover 180 km distance. What is the speed of Harsha?
(A) 12 km/h
(B) 10 km/h
(C) 15 km/h
(D) 20 km/h
Trick:
S1 x(S1+5)= 180 * 5/3 
S1=15 km/h