4 There are only red sweets and yellow sweets in a bag. There are n red sweets in the bag.
There are 8 yellow sweets in the bag.
Sajid is going to take at random a sweet from the bag and eat it.
7
He says that the probability that the sweet will be red is
10
7
(a) Show why the probability cannot be
10
After Sajid has taken the first sweet from the bag and eaten it, he is going to take at
random a second sweet from the bag.
Given that the probability that both the sweets he takes will be red is
uw
(b) work out the number of red sweets in the bag.
You must show all your working.