# Numbers & Algebra - Numbers and Algebra MCQ

16:

A ball is dropped from a height of 12 m and it rebounds 1/2 of the distance it falls. If it continues to fall and rebound in this way, how far will it travel before coming to rest?

 A. 36 m B. 30 m C. 48 m D. 60 m Answer Report Discuss Option: A Explanation : Total distance travelled by the ball before coming to rest = 12 + 2 (6 + 3 + 1.5 +...to?) = 12 + 2. ( 6/ (1-1/2)) = 12 + 2(12) = 36m Click on Discuss to view users comments. Write your comments here:
17:

Sum of three prime numbers is 100. If one of them exceeds another by 36, then one of the numbers is

 A. 7 B. 29 C. 41 D. 67 Answer Report Discuss Option: D Explanation : x + (x + 36) + y = 100 ⇒2x + y = 64 Therefore y must be even prime which is 2  2x + 2 = 64 ⇒x = 31. ∴ Third prime number = x + 36 = 31+ 36 = 67 Click on Discuss to view users comments. Write your comments here:
18:

A school has 5 divisions in a class IX having 60, 50, 55, 62 and 58 students. Mean marks obtained in a History test were 56, 64, 72, 63 and 50 by each division respectively. What is overall average of the marks per students?

 A. 56.8 B. 58.2 C. 62.4 D. 60.8 Answer Report Discuss Option: D Explanation : Average = (60x56+50x64+55x72+62x63+58x50)/ (60+50+55+60+58 ) = (3360+3200+3960+3906+2900)/285 = 60.8 Click on Discuss to view users comments. Write your comments here:
19:

What is the smallest number which when increased by 3 is divisible by 27, 35, 25 and 21?

 A. 4722 B. 4725 C. 4728 D. 4731 Answer Report Discuss Option: A Explanation : L.C.M. of 27, 35, 25 and 21 = 4725 ∴ Number = 4725-3 = 4722. Click on Discuss to view users comments. Write your comments here:
20:

A tiled floor of a room has dimensions  m * m sq.m. Dimensions of the tile used are n * n sq.m. All tiles used are green tiles except diagonal tiles which are red. After some years some green tiles are replaced by red tiles to form an alternate red and green tile pattern. How many green tiles are removed?
(m  ≠ n and total number of tiles are odd).

 A. B. C. D. Answer Report Discuss Option: B Explanation : Total red tiles initially Total number of tiles As number of red tiles > number of green tiles  (since room has odd number of tiles and corner tiles are red) Hence total red tiles required to form an alternate pattern ∴ Number of green tiles removed Click on Discuss to view users comments. Write your comments here: