Are they right?

#1
I have a homework assignment I need help on.
Can you guys check my answers?

1. Assume that you bought a ticket and your bro bought two. There were 1000 tickets sold.

A. What is the probability that you will win the grand prize? 1/1000 = 0%
B. What is the probability that your brother will win? 2/1000 = 0%
C. What is the probability either of you will win? 3/1000 = 0%


2. If mother looks at kid two hours a day and baby looks at mom a total of 3 hrs a day, what is the probability they will look at each other the same time?
2/24 X 3/24 =.01

3. Subject presented with 5 buttons. He must learn to press a certain three of them in a predetermined order. What chance does the subject have of pressing correctly on the first try.
nPr = 5P3=60

4. 20 question true and false test is given. One student gets 11 answers correct. Do we have any reason to believe he has done anything other than guess?
No because the events are mutually exclusive.

Thanks!
 

Mean Joe

TS Contributor
#2
I would say keep your answers in fraction form (eg 1/1000) rather than rounding off %. Everything looks good.

For #3 make sure you present answer as 1/60.

For #4 it's not because the events are mutually exclusive. There's no reason to believe student didn't just guess, since he only did insignificantly better than someone answering randomly.