Quantitative Aptitude - Arithmetic Ability Questions

A can complete the work in 12 days working 8 hours a day

=> Number of hours A can complete the work = 12×8 = 96 hours 

=> Work done by A in 1 hour = 1/96

B can complete the work in 8 days working 10 hours a day

=> Number of hours B can complete the work = 8×10 = 80 hours 

=> Work done by B in 1 hour = 1/80

Work done by A and B in 1 hour = 1/96 + 1/80 = 11/480

 => A and B can complete the work in 480/11 hours

A and B works 8 hours a day.

Hence total days to complete the work with A and B working together 

= (480/11)/ (8) = 60/11 days

Let the present age of Ravali = x

=> Swarna's present age = x - 9

From the given data,

x + 7 = 2(x - 9 + 7)

=> x = 11 yrs

Required Ravali's age after 4 years = 11 + 4 = 15 yrs.

Total numbers in die=6

P(multiple of 2)=1/2

P(multiple of 5)=1/6

P(multiple of 2 or 5)=2/3

Let 'Y' be the youngest player.

The last song can be sung by any of the remaining 3 players. The first 3 players can sing the song in (3!) ways.

The required number of ways = 3(3!) = 4320.

Given in the question that, there are 7 boys and 6 girls. 

Team members = 5

Now, required number of ways in which a team of 5 having atleast 3 girls in the team = 

$$\begin{gathered} 6C3 x 7C2 + 6C4 x 7C1 + 6C5 \\ = 6x5x43x2x1 x 7x62x1 + 6x5x4x34x3x2x1 x 7 + 6x5x4x3x25x4x3x2x1 \\ = 420 + 105 + 6 \\ = 531. \end{gathered}$$

Annual salary of Arun = 7,68,000 Rs.
Monthly salary = 7,68,000/12 = Rs. 64,000
Spending on children = Rs. 12,000
Rest = 52,000
1/13th of the rest = 52,000/13 = Rs. 4,000 is spent on food.
Rs. 8,000 is spent in mutual funds.
Monthly savings = 64,000 - (12,000+4,000+8,000) = Rs. 40,000.

Ratio of milk and water = 2 : 1
Quantity of milk = 60 X 2/3 = 40 litre
Quantity of water = 20 litre
To make ratio, 1: 2, we have to double the water that of milk
So, water should be 80 litre.
That means 80 – 20 = 60 litre water to be added.