Two trains of 200 m and 100 m long are running parallel at the rate of 20 m/sec. and 22 m/sec. respectively. How much time will they take to cross each other, if the trains are running along the same direction? [#1132]
Q1. Two trains of 200 m and 100 m long are running parallel at the rate of 20 m/sec. and 22 m/sec. respectively. How much time will they take to cross each other, if the trains are running along the same direction? Q1. Two trains of 200 m and 100 m long are running parallel at the rate of 20 m/sec. and 22 m/sec. respectively. How much time will they take to cross each other, if the trains are running along the same direction?
(A) 120 sec (A) 120 sec
(B) 100 sec (B) 100 sec
(C) 60 sec (C) 60 sec
(D) 50 sec (D) 50 sec
Answer: (D) 50 sec Answer: (D) 50 sec
The difference of speed = 22m/s - 20m/s = 2m/s
As the train with speed 22m/s will cross the other, hence this train have to go the smallest length of the trains distance ahead of the other to cross completely.
Hence This train will be ahead of 100m with a speed of 2m/s.
Hence The time to cross each other will take = 100m / (2m/s)
= 50 secThe difference of speed = 22m/s - 20m/s = 2m/s
As the train with speed 22m/s will cross the other, hence this train have to go the smallest length of the trains distance ahead of the other to cross completely.
Hence This train will be ahead of 100m with a speed of 2m/s.
Hence The time to cross each other will take = 100m / (2m/s)
= 50 sec
Q1. A 20 m long ladder is leaning on a vertical wall. It makes an angle of 30° with the ground. The height of the point the ladder touches wall is Q1. A 20 m long ladder is leaning on a vertical wall. It makes an angle of 30° with the ground. The height of the point the ladder touches wall is
Q2. If the average age of A, B and C is 22 years and the average age of B and C is 25 years, then find the age of A after 9 years from now. Q2. If the average age of A, B and C is 22 years and the average age of B and C is 25 years, then find the age of A after 9 years from now.
(A) 25 years (A) 25 years
(B) 35 years (B) 35 years
(C) 50 years (C) 50 years
(D) 45 years (D) 45 years
Answer: (A) 25 years Answer: (A) 25 years
25 years
=> A+B+C = 22*3
=> A+(B+C) = 66
=> A+(25*2) = 66
=> A = 66-50
=> A = 16
After 9 years A = 16+9 = 25 years25 years
=> A+B+C = 22*3
=> A+(B+C) = 66
=> A+(25*2) = 66
=> A = 66-50
=> A = 16
After 9 years A = 16+9 = 25 years
Q3. What is the name of the mathematical concept that describes a value that never changes, like the ratio of a circle's circumference to its diameter? Q3. What is the name of the mathematical concept that describes a value that never changes, like the ratio of a circle's circumference to its diameter?
(A) Variable (A) Variable
(B) Constant (B) Constant
(C) Fraction (C) Fraction
(D) Decimal (D) Decimal
Answer: (B) Constant Answer: (B) Constant
A constant is a mathematical concept that represents a value that remains unchanged, like pi (π), which is approximately 3.14 and never changes.A constant is a mathematical concept that represents a value that remains unchanged, like pi (π), which is approximately 3.14 and never changes.
Q4. The LCM of two numbers is 40 and their HCF is 4. If the difference between the two numbers is 12, then the sum of the numbers is Q4. The LCM of two numbers is 40 and their HCF is 4. If the difference between the two numbers is 12, then the sum of the numbers is
(A) 20 (A) 20
(B) 24 (B) 24
(C) 28 (C) 28
(D) 32 (D) 32
Answer: (C) 28 Answer: (C) 28
X * (X-12) = 40 * 4
X = 20
X + (X-12) = 20 + 20 - 12 = 28X * (X-12) = 40 * 4
X = 20
X + (X-12) = 20 + 20 - 12 = 28
Q5. Two numbers are respectively 20% and 50% more than a third number. The ratio of the two numbers is Q5. Two numbers are respectively 20% and 50% more than a third number. The ratio of the two numbers is
Q8. The count of prime numbers between 80 and 100 is Q8. The count of prime numbers between 80 and 100 is
(A) 2 (A) 2
(B) 5 (B) 5
(C) 3 (C) 3
(D) 4 (D) 4
Answer: (C) 3 Answer: (C) 3
Prime numbers are numbers that are only divisible by 1 and themselves. Between 80 and 100, the prime numbers are 83, 89, and 97. Therefore, there are 3 prime numbers in this range.Prime numbers are numbers that are only divisible by 1 and themselves. Between 80 and 100, the prime numbers are 83, 89, and 97. Therefore, there are 3 prime numbers in this range.
Q9. Select the number pair in which the two numbers are related in the same way as 35 : 6. Q9. Select the number pair in which the two numbers are related in the same way as 35 : 6.
Q10. Find the least number by which 1250 must be multiplied to make it a perfect square. Q10. Find the least number by which 1250 must be multiplied to make it a perfect square.
