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 |
Option: D Explanation : Average = (60x56+50x64+55x72+62x63+58x50)/ (60+50+55+60+58 ) = (3360+3200+3960+3906+2900)/285 = 60.8 |
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 |
Option: A Explanation : L.C.M. of 27, 35, 25 and 21 = 4725 ∴ Number = 4725-3 = 4722. |
Which of the following is true?
A. | Sum of four consecutive even numbers is always divisible by 8. |
B. | Sum of four consecutive odd numbers is always divisible by 8. |
C. | Product of any n consecutive natural numbers may not be divisible by n!. |
D. | Product of 4 consecutive odd numbers is always divisible by 15. |
Option: B Explanation :
(A) Four consecutive even numbers can be written as 2n, 2n + 2, 2n + 4 and 2n + 6,where n is any natural number. |