Question

Seema types \[270\] words in half an hour. How many words would she type in $5$ minutes?
(a) 36
(b) 45
(c) 40
(d) 50

Answer 1

Hint: This question is fully based on unitary method. Firstly we calculate half an hour into minute using the formula –
$1$ hour $=$ $60$ minutes.
We will get an hour in minutes. Then we calculate Seema’s number of typed words in one minute by using the unitary method. Then by multiplying we get the number of words typed by her in $5$minutes.

Complete step by step answer:
Let us look into the concept of the unitary method. It is a method for solving a problem by first finding the value of a single unit and then finding the necessary value by multiplying the single unit value.
So, now we know that there are $60$ minutes in an hour, and half an hour means half of an hour. So,
Total time $=\dfrac{1}{2}hour$.
But $1$ hour $=$ $60$ minutes, so time $=\dfrac{60}{2}$ minutes
$=30$ minutes.

Now, according to the question, Seema types $270$ words in half an hour, which means she types $270$ words in $30$minutes.

Since, Seema types in $30$ minutes $=270$ words.
By unitary method,
She types in $1$ minute $=\dfrac{270}{30}$ words
$=90$ words.
So,
She will type in $5$ minutes $=9\times 5$ minutes
$=45$ minutes.

Hence, Seema types $45$ words in $5$ minutes.
Thus, the correct option is (b).

Note:
In this type of question, students should take care of multiplication and division in the unitary method. A silly mistake in any calculation can change the whole answer into wrong. We also have to take care of time conversion, and also what time is given.