Question

Hi, I am just doing some maths revision in light of my maths GCSE resit, which is very soon. I am sitting the higher paper for the first time, so some of the questions towards the end of the paper are very testing of my knowledge.

At the moment I am going over past papers and I have come stuck on a question. After looking through my books, I am yet to understand what the question is asking. if anyone could help me I would be eternally grateful!

Question:

Ten different names are put into a computer. One of the names is Jaspal.

a) On Monday, the computer chooses two names at random. the computer is set so that the same name CAN be chosen twice.

Show the probability that Jaspal is chosen at least once is 19/100.
(3 marks)

b)On Tuesday, the computer chooses two names at random. The computer is set so the name CANNOT be chosen twice.

Work out the probability that Jaspal is chosen now.
(3 marks)

Any help would be really appreciated! Thank you
Kind regards
Sam.

Answer 1

a) It's 1-probability of not choosing Jaspal

= 1 - (9/10)^2 = (100-81)/100 =

19/100