We call a number perfect if it is the sum of all its positive divisors, except itself. e.g., 28 is a perfect number because 28 = 1 + 2 + 4 + 7 + 14. Which of the following numbers is a perfect number?

• 9

• 6

• 13

• 10

Which of the following numbers is a perfect square?

• 548543251

• 548543241

• 548543213

• 548543215

73.

If a set A contains 5 elements then, the number of subsets of A where none of the subset is empty set, is

• 32

• 16

• 64

• 31

The polynomial

$\mathrm{P}\left(\mathrm{x}\right) = {\mathrm{x}}^4 - 2{\mathrm{x}}^3 + 3{\mathrm{x}}^2 - \mathrm{ax} + 3\mathrm{a} - 7$

when divided by (x + 1) leaves the remainder 19. The value of a is

• 3

• 2

• 5

• 4

The abscissa of the point( - 2, - 5) is

• 2

• - 2

• 5

• - 5

There are three sections A, B and C in Class X with 25, 40 and 35 students respectively. The average marks obtained "by sections A, B and C are 70%, 65% and 50% respectively. The average marks of entire Class X is

• 60%

• 61%

• 61.66%

• 65%

The given Pie-chart shows the marks scored by a student in different subjects in an examination. If the total marks obtained by the student be 648, then marks scored in English, Science and Social Science exceed the marks scored in Hindi and Mathematics by

• 66

• 54

• 48

• 30

$\mathrm{If} (3\mathrm{a} + 5\mathrm{b}) : (3\mathrm{a} - 5\mathrm{b}) = 5 : 1, \mathrm{then} \mathrm{the} \mathrm{value} \mathrm{ofa} : \mathrm{b} \mathrm{will} \mathrm{be}$

• 3 : 2

• 5 : 3

• 2 : 1

• 5 : 2

The production of company X is 120% of the production of company Y and 80% of the production of company Z. The respective ratio between the production of companies X, Y and Z is

• 4 : 3 : 5

• 6 : 5 : 9

• 10 : 9 : 12

• 12 : 10 : 15

A shopkeeper sells 25 books at the rate of Rs 45 per book after giving 10% discount and gain 50% profit. If the discount is not given, then profit per cent will be

• 60

• 66

• $66\frac{1}{3}$

• $66\frac{2}{3}$