**651. The ratio of two numbers a and b is 3:5. If 2 is added to both the numbers, the ratio becomes 2:3. Find b.**

A. 15**B. 10**

C. 8

D. 5

**Explanation****a:b = 3:5 5a = 3b (a+2):(b+2) = 2:3 3(a+2) = 2(b+2) 3a+6 = 2b+4 3*(3b/5) = 2b-2 9b = 10b-10 b =10**

**652. The plan for a rectangular area is drawn to a scale of 1:500. If the length and breadth in the plan is 30 cm and 20 cm, find the actual area.**

A. 1200 m²

B. 1500 m²

C. 12000 m²**D. 15000 m²**

**Explanation:****Actual length****= 30*500 cm Actual breadth****= 20*500 cm Actual area****= 30*20*500*500 = 15000 m²**

**653. The length and breadth of a rectangle are in the ratio 5:4. Find its perimeter if its area is 180 cm²****A. 54 cm**

B. 27 cm

C. 12 cm

D. 15 cm

**Explanation:****Let the length and breadth be 5x cm and 4x cm.****5x*4x=180****20x²=180****x²=9,x=3 Length = 15cm Breadth = 12cm Perimeter****= 2(l+b)****= 2*27****= 54 cm**

**654. In what ratio should the profit of Rs.8000 be divided if X starts a business with an investment of Rs. 20000, Y invests Rs.7500 for 4 months and Z invests Rs.15000 after 3 months from the start of the business.**

A. 16 : 2 : 3

B. 8 : 3 : 6**C. 16 : 2 : 9**

D. 6 : 9 : 1

**Explanation:****Let the profit of X be P1, that of Y be P2 and of Z be P3.****P1:P2:P3 = 20000*12 : 7500*4 : 15000*9 = 240 : 30 : 135 = 80 : 10 : 45****= 16 : 2 : 9**

**655. M:N = 3:4, N:O = 5:7 and O:P = 7:9. Then M:P =________?**

A. 1/3

B. 7/9**C. 5/12**

D. None of these

**Explanation:****M/P = M/N * N/O * O/P = ¾ * 5/7 * 7/9 = 5/ 12**

**656. The perimeter of a triangle is 81 cm. If the sides are in the ratio 4:3:2, find the length of the largest side.**

A. 45 cm

B. 40 cm**C. 36 cm**

D. 27 cm

**Explanation:****Let the three sides be 4x,3x and 2x. 4x+3x+2x = 81 9x = 81 x = 9 Length of the largest side****= 4x = 36 cm**

**657. The ratio of boys and girls in a class was 11:13. 8 girls and 4 boys join the class from this academic year and the ratio becomes 4:5. Find the strength of the class.**

A. 96

B. 68

C. 72**D. 108**

**Explanation:****Let the number of boys and girls in the class be 11x and 13x. 4 boys and 8 girls join the class. Strength of the class****= 11x+13x+4+8****= 24x+12 (11x+4):(13x+8) = 4:5 5*(11x+4)=4*(13x+8) 55x+20=52x+32 3x=12 x=4 24x+12=108**

**658. A class has 90 students. If the ratio of boys and girls is 7:8, find the number of boys in the class.**

A. 48**B. 42**

C. 60

D. 70

**Explanation:****7x+8x=90 15x=90 x=6 Number of boys=7x=42**

**659. In a partnership for a business, Changaz invests Rs.6000 for complete year & Nasir invests Rs.3000 for 6 months. What is Nasir’s share if they earn Rs.240 as profit?**

A. 120

B. 80

C. 192**D. 48**

**Explanation:****If A invests amount C1 for T1 time and his share of profit is P1, and B invests amount C2 for T2 time and his share of profit is P2, then, C1 * T1 / C2 * T2 = P1/P2****If P is the Nasir’s share of profit, then Changaz gets (240 – P)****Therefore, 6000 * 12 / 3000 * 6 = (240 – P) / P = 72/ 18 = 4****4P = (240 – P)****5P = 240****P = 48**

**660. If x% of 200=y% of 250, find y:x.**

A. 5:4

B. 5:2

C. 2:5**D. 4:5**

**Explanation:****(x/100)*200 = (y/100)*250 y/x = 20/25 = 4/5 y:x=4:5**