A red light flashes 3 times per minute and a green light flashes 5 times in two minutes at regular intervals. - General Test

Advertisements
Advertisements
MCQ

A red light flashes 3 times per minute and a green light flashes 5 times in two minutes at regular intervals. If both the lights start flashing at the same time, how many times do they flash together in each hour?

Options

  • 30

  • 24

  • 20

  • 60

Advertisements

Solution

30

Explanation:

In one minute or 60 seconds, red light flashes 3 times, i.e. it flashes after every 20 sec. `[60/3 = 20]`.

Similarly, green light flashes in every `(2 xx 60)/5` 24 sec.

L.C.M. of (20, 24) = 120 sec.

Hence both will flash together after every 120 sec.

In 1 hour or 60 × 60 = 3600 seconds, they will flash together `3600/120` = 30 times.

Concept: Number System (Entrance Exam)
  Is there an error in this question or solution?

RELATED QUESTIONS

Solve the following question and mark the best possible option.
If x, y, z are positive real numbers, such that x + y + z = 25, then the maximum value of `1/x + 1/y + 1/z` is


Solve the following question and mark the best possible option.
Find 3x2y2 if x and y are integers such that y2 + 3x2y2 = 30x2 + 517.


The value of 1 + `1/4 + 1.3/4.8 + (1.3.5)/(4.8.12) + ........` is :


`(("cos"  30  theta + "i" "sin" 30  theta)^5 ("cos"  20  theta + "i"  "sin" 20 theta)^4)/(("cos"  theta + "i"  "sin"  theta)^-4("cos"  theta  "i"   "sin"  theta)^6)` is equal to:


The real part of cos h (αα - iββ) is


Which of the following fractions has the highest value 3/5, 4/3, 2/5, 1/2


Three consecutive positive even numbers are such that thrice the first number exceeds double the third by 2, the third number is


P, Q, and R are three consecutive odd numbers in ascending order. If the value of three times P is 3 less than two times R. Find the value of R.


A number of students who have opted for subjects A, B, and C are 60, 84, and 108 respectively. The examination is to be conducted for these students such that only the students of the same subject are allowed in one room. Also, the number of students in each room must be the same. What is the minimum number of rooms that should be arranged to meet all these conditions?

The difference between the place values of two 7s in the numeral 69758472 is


Which one of the following is not a prime number?


The largest 5-digit number exactly divisible by 91 is


Which natural number is nearest to 9217 which is completely divisible by 88?


n is a whole number which when divided by 4 gives 3 as remainder. What will be the remainder when 2n is divided by 4?


The unit digit in the product (784 x 618 x 917x 463) is


The HCF of two numbers is 11 and their LCM is 7700. If one of the numbers is 275, then the other is


In GP find 1 + `1/2`+ `1/4` + ... up to 5 terms.


Which one of the following numbers is completely divisible by 99?


Which of the following numbers should be added to 11158 to make it exactly divisible by 77?


The smallest number which when divided by 9, 12 and 16, leaves remainder 5 is


If x and y are natural numbers such that x + y = 2017, then what is the value of (−1)x + (−1)y?


Let x = (633)24 − (277)38 + (266)54. What is the unit's digit of x?


The smallest number added to 680621 to make the sum a perfect square is ______.


If the fractions `5/14, 6/11, 7/9, 8/13` and `9/10` are arranged in ascending order of their values, which one will be the fourth?


If `11 5/21` is subtracted from `15 3/14` and the difference is multiplied by 504, what will be the number?


Find the least number by which 77, 175 should be divided to make it a perfect cube number.


In an office, there are 108 tables and 132 chairs. If `1/6` of the tables and `1/4` of the chairs are broken, how many people can work in the office if each person requires one table and one chair?


If 9 mangoes cost as much as 5 oranges, 5 oranges as much as 3 apples, 4 apples as much as 9 pineapples and if 3 pineapples cost ₹ 48, what will a mango cost?


If a + b > c + d and b + c > a + d then it is definite that


2 oranges, 3 bananas and 4 apples taken together cost ₹ 15.00. 3 oranges, 2 bananas and 1 apple cost ₹ 10.00. Then the cost of 3 oranges, 3 bananas and 3 apples cost.


Share
Notifications



      Forgot password?
Use app×