Question

About 1 billion people around the world have Facebook on their mobile phones. People spend on average 30 minutes per day accessing Facebook on their phones. Estimate (to 2 sig figs) how many million people around the world are accessing Facebook via their phone at this moment.

(give your answer to 2 sig fig, but NOT in scientific notation. If, for example, you thought the answer was 1 million people, give your answer as 1.)

Answer 1

Solution-

According to question,

Since on an average people spend 30 minutes in face book.

And we know that 1 day =24 hours = 24×60 =1440 minutes

Now, the Probability that a person is using face book is

= 30/1440

=1/48

Now, since number of people used facebook

=I billion =1000 million

So, at this moment number of people using facebook is

=No. of people using fb× P(a person is using fb)

=1000×1/48 million

=20.83 million

≈ 21 million.

Hence, about 21 million people are using facebook at this moment.