What is the probability that a randomly selected reference book is hardcover? 0.25 0.4 0.6 0.75

0.4

Step-by-step explanation:

 The correct option is (B) 0.4.

Step-by-step explanation:  We are given to find the probability that a randomly selected reference book is hardcover.

Let, S denote the sample space for the experiment of selecting a book.

Then, n(S) = 60.

Let A denote the event that the selected book is is a reference one and B denote the event that the selected book is a hardcover.

Then, according to the given information, we have

So,

Therefore, the probability that a randomly selected reference book is hardcover is equal to the conditional probability of event B given A.

That is, the required probability is

Option (B) is correct.

answer: first option i.e. 'a' is correct.

step-by-step explanation:

since we have given that

number of minutes to wrap a small gift box = 4 minutes

we need to find the number of gifts to be wrapped in 5 minutes

since there is a direct variation, as the number of minutes will increase with   number of gifts to be wrapped.

so, let the number of gifts to be wrapped in 5 minutes be x.

so, it becomes,

hence, first option 'a'   is correct.