Need help with combination! (1 Viewer)

[thgus2114]

Q1. Phuong takes the 4 aces from
a deck of cards and randomly
selects an ace out of these 4 cards
over 100 experiments.

Find the probability that
he selects the ace of hearts this
number of times (to 3 significant
figures).


Q2. One bag contains 5 blue and
3 yellow balls and another bag
contains 7 blue and 2 yellow balls.

A bag is chosen at random
and a ball drawn out. What is the
probability that it is blue?

 

[BenHowe]

For q1, you can do it by combinatorics or recognise it's just a binomial distribution. I don't know how many times you want lol, but just use the formula

For q2, the best way to do these questions is to set up clear event notation:

Let Bi be the event the ball selected is done so from bag i, i=1,2
Let B be the event the ball selected is blue
Let Y be the event the ball selected is yellow

We require P(B)

The easiest way for you to think about this is just to consider the 2 ways you can get a blue ball i.e. P(B)=P(B1)P(B |B1)+P(B2)P(B | B2)

Does the expression make sense? You should be able to proceed from there.

As an extension, given that the ball selected was yellow, what's the probability it was drawn from bag 1?

 

[thgus2114]

Thank you for your help but I'm still a bit confused with Q1. Can someone please explain it further?

 

[InteGrand]

Thank you for your help but I'm still a bit confused with Q1. Can someone please explain it further?