**Questions:**

**1.(5 marks) A press release from Gartner indicates that 79.0% of all smartphones sold in the second quarter of 2013 were Android, and 14.2% of all smartphones sold in the second quarter of 2013 were iOS:**

http://www.gartner.com/newsroom/id/2573415

If 30 smartphones sold in the second quarter of 2013 are randomly selected:

- Find the probability that less than 5 are iOS.
- Find the probability that 20 or 21 are Android.
- Find the probability that at least 22 are Android.
- Find the probability that exactly 3 have an operating system that is not iOS and not Android.

**2.(5 marks) Recent YouTube statistics show that an average of 100 hours of video are uploaded to YouTube every minute:**

http://www.youtube.com/yt/press/statistics.html

- Determine the probability that 99 hours of video are uploaded to YouTube in the next minute.
- Determine the probability that 100 or 101 or 102 hours are uploaded to YouTube in the next minute.
- Determine the probability that less than 99 hours of video are uploaded to YouTube in the next minute.
- Determine the probability that more than 102 hours of video are uploaded to YouTube in the next minute.

**3.(5 marks) A recent post by eMarketer.com indicates that the amount of time that US adults spend on nonvoice mobile activities per day is normally distributed with a mean of 2.35 hours and a standard deviation of 0.89 hours.**

http://www.emarketer.com/Article/Digital-Set-Surpass-TV-Time-Spent-with-US-Media/1010096

If a US adult is randomly selected:

- Determine the probability that he/she spends between 1.50 and 3.00 hours per day per day on nonvoice mobile activities.
- Determine the probability that he/she spends less than 1.00 hour per day per day on nonvoice mobile activities.
- Determine the probability that he/she spends more than 2.50 hours per day per day on nonvoice mobile activities.
- Determine the probability that he/she spends between 4.00 and 5.00 hours per day per day on nonvoice mobile activities.

**4.(5 marks) Determine the probability of flipping 60 or more tails out of 100 flips of a fair coin using a:**

- Binomial distribution.
- Poisson distribution with
*µ*=50.
- Normal distribution with
*µ*=50 and σ =5.