সোমবার, ১৪ সেপ্টেম্বর, ২০১৫

Solve Math Problems Without Using Calculator (Part1)

Some of the private banks disallow calculator in the exam hall. They want us to solve math problems without using calculator. I have given some examples below. Try to solve following math problems without the help of a calculator. 

1) Sanwar spent 20% of his salary for food, 30% for apartment rent, and 25% for other expenses. If the remaining Tk. 3500 were his monthly savings, how much (taka) was his apartment rent?
a)      3600
b)      4200
c)      2400
d)     4500
Correct Answer: 4200 Taka
Shortcut Solve: when saving 25 total salary 100; when 1 total 100/25; when 3500 total (100X3500)/25= 14000 Taka; Apartment rent = 14000X30% = 4200. 



2) Two number when divided by a certain divisor leave a remainders of 271 and 159 respectively. When the sum of these two numbers is divided by the same divisor, the remainder is 147. What is the divisor?
a)      283
b)      258
c)      237
d)     204
Correct Answers: 283
Shortcut Solve : (271+159) – 147 = 283

3) If it takes Sohel 6 days to paint the apartments of a building and it takes Kamal 8 days to do the same job, how long would it take to do the job if both painters worked together simultaneously?
a)      18/7 days
b)      24/7 days
c)      32/7 days
d)     48/7 days

Correct Answer: 24/7 days
Shortcut Solve: 6X8/6+8 = 24/7 days

4) A vendor sells 60 percent of mangoes he has and distributes 15 percent of the remainder to the poor. Next day he sells 50 percent of the remainder and distributes the rest to the poor. What percent of his mangoes did the vendor distribute to the poor in two days?
a)      35%
b)      36%
c)      23%
d)     17% 
Correct Answer: 23 Percent
Shortcut Solve: First day sell (100X60%)=60, remains 40; Gave poor 40X15% = 6, remains 34; Second day sell (34X50%) = 17, remains 17; So Total game poor people 6+17=23

5) If the area of a square with sides of length 8 centimeters is equal to the area of a rectangle with a width of 4 centimeters, what is the perimeter of the rectangle in centimeters?
a)      20
b)      40
c)      32
d)     19
Correct Answer: 40
Shortcut Solve: Area of the Square 8X8=64; Area of a rectangle 4X x = 4x, so 4x= 64; x = 64/4=16; so Perimeter = 2(16+4) = 40

6) If 2/X = 5 and 3/Y = 15, then x-y = ?
a)      1/3
b)      3/5
c)      4/15
d)     1/5
Correct Answer: 1/5
Shortcut Solve: x = 2/5; y = 3/15 = 1/5; x-y = 2/5-1/5 = 1/5

7) An NGO hired some volunteers. If 55% of the volunteers hired were male, and the remaining 180 were female, how many volunteers were hired?
a)      450
b)      400
c)      480
d)     320 
Correct Answer: 400
Shortcut Solve: (180X100)/45 = 400

8) The average of x and y is 40 and the average of y and z is 35. What is the value of x-z?
a)      5
b)      10
c)      20
d)     34
Correct Answer: 10
Shortcut Solve: x+y = 80 (Because their average is 40) ; (x+y = 80 ) – (y-z=70) = x-z = 10

9) The average (arithmetic mean of 8 numbers is 6. When two more numbers are added to the 8 numbers, the new average of all the 10 numbers is 7. What is the average of the two numbers added
a)      12
b)      15
c)      11
d)     22
Correct Answer: 11
Shortcut Solve: (6X8) = 48; (10X7) = 70; 70-48= 22; 22/2 = 11

10) In what ratio should a 20% sugar solution be mixed with a 50 % sugar solution so that the resultant solution has 40% sugar in it?
a)      1:2
b)      2:1
c)      1:5
d)     1:4
Correct Answer: 1:2
Shortcut Solve: 50-40 = 10; 40-20=20; ration = 10:20 = 1:2