Ans. 
5 = 3 + (13 + 1)
15 = 5 + (23 + 2)
45 = 15 + (33 + 3)
113 = 45 + (43 + 4)
? = 113 + (53 + 5), i.e. ? = 243

Half of the cloth = 37.5/2
From 1 meter he will make 8 pieces
=> in 37.5/2 ---- ?

37.5/2 x 8

= 150.

In these type of fractions, the decimal moves left the number of zeroes in the divisor times. Herein the given question 18/1000, there are 3 zeros in 1000 (divisor). Hence, the quotient is 0.018.

The quotient of 18/1000 = 0.018.

Albatross

Let the least value of the prize = Rs. x

Then the next value of the prize is x+30 , x+60, x+90, ....x+240.

Given total amount of cash prizes = Rs.1890

--> x + (x+30) + (x+60) + (x+90) + ....+ (x+240) = 1890

--> 9x + (30 + 60 + 90 + 120 + 150 + 180 + 210 + 240) = 1890

--> 9x + 30(1 + 2 + 3 + 4....+ 8) = 1890

--> 9x + 30(36) = 1890

--> 9x = 810 --> x=90

Hence the least value of the prize x=90

Let the total women in the group be 'W'

Then according to the given data,

 W x 20 = (W-12) x 32

 => W = 32 

Therefore, the total number of women in the group = 32