Answer: B) 29.39 cm Explanation: Volume of water flowing through 1 pipe of diameter x = Volume discharged by 6 pipes of diameter 12 cms.   As speed is same, area of cross sections should be same.    Area of bigger pipe of diameter x = Total area of 6 smaller pipes of diameter 12  i.e πR2 = 6πR12    Here R = R and R1 = 12/2 = 6    ⇒R2 = 6×6×6    R = 14.696    => D = X = 14.696 * 2 = 29.3938 cm.

Answer: C) 4 Explanation: Let the required number be 'N' given that its quarter i.e; N/4 exceeds its double i.e, 2N by 7 => N/4 + 7 = 2N => N + 28 = 8N 7N = 28 N = 4.

Answer: C) 6! x ⁷P₆ Explanation: We can initially arrange the six boys in 6! ways.Having done this, now three are seven places and six girls to be arranged. This can be done in ⁷P₆ ways. Hence required number of ways = 6! x ⁷P₆

Answer: A) 36 days Explanation: Given the ratio of efficiencies of P, Q & R are 3 : 8 : 5 Let the efficiencies of P, Q & R be 3x, 8x and 5x respectively They can do work for 12 days. => Total work = 12 x 16x = 192x   Now, the required time taken by Q to complete the job alone = 162x8x = 24 days.

Answer: D) 363 Explanation: The given numbers in the series follows a pattern that, 3 (3 x 3) + 3 = 12 (12 x 3) + 3 = 39 (39 x 3) + 3 = 120 (120 x 3) + 3 = 363.

Answer: C) 209 Explanation: We may have (1 boy and 3 girls)or(2boys and 2 girls)or(3 boys and 1 girl)or(4 boys). Required number of ways = (C16× C34) + C26×C24  + (C36× C14) + (C46)   = (24+90+80+15)  = 209.

Answer: D) 90% Explanation:

Answer: C) Both A & B Explanation: Covalent bonds hold atoms together because the attraction between the positively charged nuclei and the negatively charged shared electrons is greater than the repulsions between the nuclei themselves.