GRE Questions

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You have to actually count all the balls in the pyramid.
Simple way is to count the balls in each level.

So lower most level lets say 1st level has 4 x 4 balls; i.e. 16 balls
Similarly 2nd level has 3 x 3 balls; i.e. 9 balls.
3rd level has 2 x 2 balls; i.e. 4 balls.
The top most level has just 1 ball.

So the total number of balls is 16+9+4+1 = 30.

So the image has 30 Balls in all.

Let the age of ruler is x so that of son = x/2 (given)
Now according to the given condition
(x/6) + (x/12) + (x/7) + 5 + (x/2) + 4 = x
=> x = 84

Let the total Profit be Z.
Ramu's profit share is 2/3 of profit (i.e 2Z/3)
Ravi's profit is (Z-2Z/3) =Z/3
Hence the profit ratio is , Ravi : Ramu = Z/3 : 2Z/3 = 1:2

Let total Capital be Rs.X and Ramu has contributed for Y months.Since Ramu's profit share is 2/3, his invest share will be 2/3 in capital.

Ravi's invest for 16 months / Ramu's invest for Y months = Ravi's profit share / Ramu's profit share
i.e. (X/6 x 16) / (2X/3 x Y) = 1/2

Solving the above equation, we get Y = 8.
So Ramu's money has been used for 8 months.

1/15 + 1/12 + 1/R = 1/6, we got R = 60 (it means R will take 60 days to complete the work alone)

so ratio of work done by P:Q:R = 1/15 : 1/12 : 1/60 = 5 : 4 : 1

so R share = (1/10) x 1200 = 120.

Total work is given by L.C.M of 72, 48, 36

Total work = 144 units

Efficieny of A = 144/72 = 2 units/day

Efficieny of B = 144/48 = 3 units/day

Efficieny of C = 144/36 = 4 units/day

According to the given data,

2 x p/2 + 3 x p/2 + 2 x (p+6)/3 + 3 x (p+6)/3 + 4 x (p+6)/3 = 144 x (100 - 125/3) x 1/100

3p + 4.5p + 2p + 3p + 4p = 84 x 3 - 54

p = 198/16.5

p = 12 days.

Now, efficency of D = (144 x 125/3 x 1/100)/10 = 6 unit/day

(C+D) in p days = (4 + 6) x 12 = 120 unit

Remained part of work = (144-120)/144 = 1/6.

1 < 4n + 7 < 200

n can be 0, or -1

n cannot be -2 or any other negative integer or the expression 4n + 7 will be less than1.

The largest value for n will be an integer < (200 - 7) /4

193/4 = 48.25, hence 48

The number of integers between -1 and 48 inclusive is 50

When their is a colloid in the solution, then it will show the Brownian movement, such as dust particle in the air will show the Brownian movement.

Hence, Brownian movement arises due to the impact of the molecules of the dispersion medium with the colloidal particles. It has been postulated that the impact of the molecules of dispersion medium on the colloidal particles are unequal.

This leads to the zig-zag (random) motion of the colloidal particles.