GATE Questions

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The panchatantra was written by Vishnu sharma, an Indian scholar during the period of Gupta rule. It is during 3rd Century BCE.

Given speed of the person = 8 1/2 = 17/2 kmph
Let the speed of the stream = x kmph
speed of upstream = 17/2 - x
speed of downstream = 17/2 + x
But given that,
2(17/2 - x) = 17/2 + x
=> 3x = 17/2
=> x = 2.83 kmph.

Let the leak will empty the tank in x hrs 

Then, 1/9 - 1/x = 1/13

x = 29.25 hrs

Given the average age of couple and their son = 40

=> Sum of age (H +W +S) = 40×3

Let the age of daughter in law at the time of marriage = D years

Now after 10 years,

(H + S +W) + 3×12 + D +12 + 10 = 38×5

178 + D = 190

D = 190 -178 = 12 years

12 year old Manish is three times as old as his brother Rajeev who must be 4 years old.
Diff in ages = 8 years.
when Rajeev will become 8 years old, Manish will be 16 yrs old and he will be twice as old as Rajeev.

Let the ratio of initial quantity of oils be 'x' => 4x, 5x & 8x.
Let k be the quantity of third variety of oil in the final mixture.
Let the ratio of initial quantity of oils be 'y'
From given details,
4x + 5 = 5y ..... (1)
5x + 10 = 7y .....(2)
8x + k = 9y ......(3)

By solving (1) & (2), we get
x = 5 & y = 5

From (3) => k = 5

Therefore, quantity of third variety of oil was 9y = 9(5) = 45kg.

Because the refractive index of glass is highest, light travels slowly in Glass. 

We know that the speed of light depends on the refraction index. The higher the index of refraction is, the slower the speed of light is.

R.I of air and vacuum = 0 (air is a teeny bit more but can be taken as 0)
R.I of water = 1.33
R.I of glass = 1.4.

Hence, Light travels slowest in Glass.

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.