Answer: C) 102 men Explanation: From the above formula i.e (m1 x t1/w1) = (m2 x t2/w2) so, [(34 x 8 x 9)/(2/5)] = [(M x 6 x 9)/(3/5)] so, M = 136 men   Number of men to be added to finish the work = 136-34 = 102 men.

Answer: A) 24000 Explanation: Let the total population be 'P' P x (96/100) = 23040 P = 240 * 100 P = 24000.

Answer: A) Total internal reflection Explanation: A periscope is an optical instrument that uses a system of prisms, lenses, or mirrors to reflect images through a tube.       Light from a distant object strikes the top mirror and is then reflected at an angle of 90 degrees down the periscope tube. At the bottom of the periscope, the light strikes another mirror and is then reflected into the viewer’s eye.   Hence, A periscope works by the principle of Total internal reflection.

Answer: D) 437 Explanation: The series follow the rule,   21 = 77 = 92-4165 = 132-4285 = 172-4 5,9,13,17,21,(+4)...In the same way next no. will be 212-4 = 441 - 4 = 437

Answer: A) 120 Explanation: 1/15 + 1/12 + 1/R = 1/6, we got R = 60 (it means R will take 60 days to complete the work alone) so ratio of work done by P:Q:R = 1/15 : 1/12 : 1/60 = 5 : 4 : 1 so R share = (1/10) x 1200 = 120.

Answer: B) 13 + 1/3 days Explanation: C alone can finish the work in 40 days.As given C does half as much work as A and B together => (A + B) can do it in 20 days(A + B)s 1 days wok = 1/20.A's 1 days work : B's 1 days Work = 1/2 : 1 = 1:2(given)A's 1 day’s work = (1/20) x (1/3) = (1/60) [Divide 1/20 in the raio 1:2]B's 1 days work = (1/20) x (2/3) = 1/30(A+B+C)'s 1 day's work = (1/60) + (1/30) + (1/40) = 9/120 = 3/40 All the three together will finish it in 40/3 = 13 and 1/3 days.

Answer: B) Rs.12,000 Explanation: We have P = 8748, R = -10 and n = 3Therefore, the purchase price of the machine= P1+R100n= 87481-101003= 8748 x (100/90) x (100/90) x (100/90)= 12,000.   Therefore, the purchase price of the machine was Rs. 12,000.

Answer: C) 10 years Explanation: Let the age of the daughter today be ‘x’ years. Mother’s age today = 3x years After 10 years, we have 3x + 10 = 2(x + 10) x = 10 years.