Question

A person has two hourglasses, one of 30 seconds and other of 1 minute which of the following time intervals can he not measure ?
(A) 30 seconds
(B) 60 seconds
(C) 50 seconds
(D) 90 seconds

Answer 1

In order to solve this problem we have to remember the concept of hourglass i.e., the measurement of these time intervals will be measured which are multiples of given time of hourglass.

Complete step by step solution:
An hourglass is a device used to measure the passage of time. Given that a person has two hourglasses of 30 seconds and 1 minute $($60 seconds$)$. So, he can measure the time in multiples of 30 and 60. So, 30, 60 and 90 seconds are the multiple of 30 and 60 seconds but 50 seconds is not the multiple of 30 and 60 seconds.

Hence, 50 seconds cannot be measured by him. So, option C is the correct answer.

Additional Information :
-Hourglass is an early device for measuring intervals of time.
-When hourglass is used in conjunction with the common log for ascertaining the speed of a ship then it is known as Sandglass or a log glass.
-It consists of two pear shaped bulbs of glass, united at their apexes and having a minute passage formed between them.

Note: Students may get confused if they do not know about hourglass. Hourglass is two connected glass bulbs with sand that slowly flows from the top bulb to the bottom bulb through a narrow passage that connects the two.The hourglass technique is really simple and actually derived from the concept of outlining but more visual and interactive in nature.