GRE Questions

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A Mirage is a naturally occurring optical phenomenon in which light rays bend to produce a displaced image of distant objects or the sky.

• It is caused due to Total internal Reflection.

• It is an optical illusion observed in deserts or hot summer days due to which a person sees a pond of water some distance ahead of him in which the surrounding objects appear inverted.

How Mirage Forms::

1. The temperature of other layers of atmosphere goes on decreasing as we go up.
2. Therefore density and refractive index of air changes as one goes up.
3. Thus a ray of light,gets refracted more and more away from the normal.
4. At a particular angle when a ray of light exceeds critical angle, total internal reflection takes place and ray of light gets reflected in the same medium.
5. when the reflected ray reaches our eye, it appears as coming from tree or sky .
6. Hence the inverted image of tree creates an impression from a pond of water.

There are 26 English Alphabets. They are:

A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z.

Therefore, from the left end the 13th letter is M and is Consonent. And from the right end the 13th letter is N and is Consonent.

Clealry, C and D sit opposite to each other. So, if A sits opposite to cook, B shall be the cook.
Now, B is to the right of barber. So, one of the rest, say C will be barber.
Clealry, then D on the opposite side shall be washerman or tailor. But, washerman is left of tailor and D on the left of A.
So, D is washerman and A is tailor.

Thus, A and B are Tailor and Cook.

The given letter equation 6 B in an O refers to 6 Balls in an Over.

So he is facing west his left hand will be in North direction.

Clearly, defence is necessary for the safety of the country, which is of prime importance. So, argument I holds. Also, a country can concentrate on internal progress and development only when it is safe from external aggressions. So, argument II does not hold.

We know that perimeter of rectangle = 2(l+b) = 2(8+7)= 30cm
Given perimeter of square is twice the perimeter of rectangle = 2(30) = 60cm
Therefore, side of the square is = 1/4 x 60 = 15cm
Circumference of the required semicircle = πr + 2r = 227× 152 + 2×152 = 23.57 + 15 = 38.57cm.