Answer: A) 2520 Explanation: The number of ways of arranging n beads in a necklace is (n-1)!2=(8-1)!2=7!2 = 2520  (since n = 8)

Answer: A) Rs. 22.5 Explanation: We know that I = PTR/100=> P = 20250/4.5 = 4500Now, new Interest at 5% = 4500x1x5/100 = 225Now the additional amount = 225 - 202.5 = Rs. 22.5

Answer: D) 36 yrs Explanation: Let present ages of Sumit=w, Krishna=x, Rishabh=y and Rohit=z , thenw+x+y = 43x3 = 129 ---(i) andw+y+z = 49x3 = 147 ---(ii)Subtracting (i) from (ii), (w+y+z) - (w+x+y)=147 -129 , z- x =18 ---(iii)Given Rohit's age => z = 54, so from (iii), x = 54-18 = 36

Answer: A) 1:1 Explanation: Quantity of alohol in the mixture = 40 x 5/8 = 25 lit Quantity of water = 40 - 25 = 15 lit According to question, Required ratio = 20 - 40 x 20100 x 5815 - 40 x 20100 x 38 + 40 x 20100 = 2015 - 3 + 8 = 1 : 1

Answer: B) 4 kmph Explanation: Let the distance in one direction = k kms Speed in still water = 4.5 kmph Speed of river = 1.5 Hence, speed in upstream = 4.5 - 1.5 = 3 kmph Speed in downstream = 4.5 + 1.5 = 6 kmph Time taken by Rajesh to row upwards = k/3 hrs Time taken by Rajesh to row downwards = k/6 hrs Now, required Average speed =Total distanceTotal speed = 2kk3 + k6 = 2k x 186k + 3k = 4 kmph    Therefore, the average speed of the whole journey = 4kmph.

Answer: C) C Explanation: It is explicitly given that all the 4 black balls are different, all the 3 red balls are different and all the 5 blue balls are different. Hence this is a case where all are distinct objects.   Initially let's find out the number of ways in which we can select the black balls. Note that at least 1 black ball must be included in each selection.   Hence, we can select 1 black ball from 4 black ballsor 2 black balls from 4 black balls.or 3 black balls from 4 black balls.or 4 black balls from 4 black balls.   Hence, number of ways in which we can select the black balls   = 4C1 + 4C2 + 4C3 + 4C4= 24-1 ........(A)   Now let's find out the number of ways in which we can select the red balls. Note that at least 1 red ball must be included in each selection.   Hence, we can select 1 red ball from 3 red ballsor 2 red balls from 3 red ballsor 3 red balls from 3 red balls   Hence, number of ways in which we can select the red balls= 3C1 + 3C2 + 3C3=23-1........(B)   Hence, we can select 0 blue ball from 5 blue balls (i.e, do not select any blue ball. In this case, only black and red balls will be there)or 1 blue ball from 5 blue ballsor 2 blue balls from 5 blue ballsor 3 blue balls from 5 blue ballsor 4 blue balls from 5 blue ballsor 5 blue balls from 5 blue balls.   Hence, number of ways in which we can select the blue balls= 5C0 + 5C1 + 5C2 + … + 5C5= 25..............(C)   From (A), (B) and (C), required number of ways=  2524-123-1

Answer: D) 10 Explanation: Here the given number series is 6, 3, 3, 4.5, 10 The odd one in the given series is 10 The pattern it follows is 6 6 x 0.5 = 3 3 x  1  = 3 3 x 1.5 = 4.5 4.5 x 2 = 9   Hence, the odd number is 10.

Answer: A) 4:3 Explanation: Given 15% of x = 20% of y => 15x = 20y => x/y = 20/15 => x : y = 4 : 3