Job Roles

The students should sit in between two teachers. There are 7 gaps in between teachers when they sit in a roundtable. This can be done in 7P6ways. 7 teachers can sit in (7-1)! ways.

 Required no.of ways is = 7P6.6! = 7!.6!

As A1 speaks always after A2, they can speak only in  1st  to 9th places and 

A2 can speak in 2nd to 10 the places only when A1 speaks in 1st place 

A2 can speak in 9 places the remaining 

 A3, A4, A5,...A10  has no restriction. So, they can speak in 9.8! ways. i.e

when A2 speaks in the first place, the number of ways they can speak is 9.8!.

When A2 speaks in second place, the number of ways they can speak is  8.8!.

When A2 speaks in third place, the number of ways they can speak is  7.8!. When A2 speaks in the ninth place, the number of ways they can speak is 1.8!

Therefore,Total Number of ways they can  speak = (9+8+7+6+5+4+3+2+1) 8! = 92(9+1)8! = 10!/2

For a triangle, we need 3 non-collinear points. So with 12 points (when all the 12 are such that any three non-collinear is12C3. But among them 8 points are collinear.

If all these 8 points are different we get 8C3 triangles as they are collinear.

In 12C3 triangles, we do not get 8C3 triangles

Therefore, The number of triangles we get = 12C3-8C3 = 164

Water has the maximum density at 4oC. So at this temperature, it sinks down to bottom and stays here. If it cools further, it will become less dense and move up. So while the upper layers can cool enough to form ice, the bottom layers remain as water at  4oC .  

Therefore, (C) is correct.

We want the temperature when F=C.

We know that, F = C x 95 + 32

So substituting C For F, we have C = -40o

Therefore,  C = -40. 

Thus when C = -40, we have C = F

Let M and m grams be the mass of boat + rock in it. By law of floatation(M+m) grams of water will be displaced. This has a volume of (M+m)cc. That means the level of water in pool has risen up by (M+m)cc with the boat + rock when it is floating. If the rocks in the boat are thrown not into the pool but outside, the weight left is only M grams the weight of the boat. This will have displaced M cc of water only i.e less water than in the case of loaded boat. But if the rocks are put in the water in the pool and not outside, then the water in the pool will rise not only by M cc on account of empty boat but also by a volume of the stone put into it. This volume will be mdwhere m is the mass of rock and d density of rock.

Now md is  < m. Thus the total rise will be M+mdwhich is < M + m.

Starting From his house, Sumanth walks 200 feet straight towards North; we can write it as N200. Similarly, the other distances and directions can be considered and written as follows : (Notice that he covers 300 yards towards East; one yard = 3 feet and hence 300 yards = 900 feet)

 N200S100E900 Adding all south and all North distances and finding the net result, and also adding all East and all West distances and finding the net result, this can further be summarized as : N100E900

 Thus, the direction from his original position is North-East.

Given,

A + B = 2C ----(i)

C + D = 2A----(ii)

Adding (i) and (ii) we get : A + B + C + D = 2C + 2A  

=>  B + D = A + C