Let the number of students be 2x, 3x and 5x.

(2x+20) : (3x+20) : (5x+20)

= 4 : 5 : 7

so,

5(2x+20) = 4(3x+20) => x = 10

Hence the total number of students before increase = 10x = 10 x 10 =100

A) 710 acres | B) 760 acres |

C) 810 acres | D) 860 acres |

Explanation:

As 12 men can reap 120 acres, 54 men will be able to reap more acres in 36 days, 120 acres of land was reaped, so in 54 days, more land will be reaped.

Thus, the numbers of acres that can be reaped by 54 men in 54 days =

A) Rs. 100 and Rs.150 | B) Rs. 150 and Rs.200 |

C) Rs.200 and Rs.250 | D) Rs.250 and Rs.300 |

Explanation:

Let the incomes of A and B be 3P and 4P.

If each saves Rs. 100 per month, then their expenditures = Income - savings = (3P - 100) and (4P - 100).

The ratio of their expenditures is given as 1 : 2.

Therefor, (3P - 100) : (4P - 100) = 1 : 2

Solving, We get P = 50. Substitute this value of P in 3P and 4P.

Thus, their incomes are : Rs.150 and Rs.200

A's spending 90% saving = 10%

B's spending 75% saving = 25%

C's spending 60% saving = 40%

Let us suppose A, B and C saves Rs. 3.5 and 6 respectively.

10% of A's saving = Rs.3

100% of A's saving = = Rs. 30

25% of B's saving = Rs. 5

100% of B's saving = = Rs. 20

40% of C's saving = Rs.6

100% of C's saving = = Rs. 15

Divide Rs. 6500 in the ratio of 30 : 20 : 15 as

A's Share = = Rs. 3000

B's Share = = Rs. 2000

C's Share = = Rs. 1500