Chapter 9 : Probability of Combined Events

Which of the following is/are dependent events?

• The pointer of a lucky wheel stops at the same sector twice consecutively

• The selection of two boys from a group of ten girls and fourteen boys at random

• Answer three objective questions with four options correctly if the answer of each question is chosen at random

• Obtain two pens of the same colour when two pens are taken out at random from a container that contains 3 red pens and 2 blue pens with replacement.

Which of the following is correct?

•  $n\left(S\right)=n\left(A\right)\times n\left(B\right)$  

•  $n\left(S\right)=n\left(A\right)+n\left(B\right)$  
  

•  $n\left(S\right)=n\left(A\right)-n\left(B\right)$  
  

•  $n\left(S\right)=\frac{n\left(A\right)}{n\left(B\right)}$  
  

Box A contains a red card and two yellow cards.

Box B contains three red cards and a yellow card.

Fauziah chooses a card from box A and box B respectively.

What are the probability of Fauziah getting both yellow cards?

• 1/6

• 2/3

• 1/4

• 2/9

According to an investigation, the probability of rainfall on Mountain X in May is 0.45.

Calculate the probability that Mountain X will have two consecutive rainy days in May.

• 0.90

• 0.55

• 0.3025

• 0.2025

A box contains 12 bulbs where two of the bulbs are burnt. Two bulbs are selected at random from the box.

Calculate the probability of getting two burnt bulbs.

• 1/36

• 1/66

• 15/22

• 25/36

Which of the following is/are the addition rule of probability?

• 
• 
• 
• 

The probability that a smartphone manufactured has a display problem is 2/13. Two smartphones are chosen at random. 

Calculate the probability that at least one smartphone chosen has a display problem. 

• 48/169

• 121/169

• 4/169

• 44/169

Seven cards labelled with the letters "G,E,M,B,I,R,A" are put in a box. A card is chosen at random from the box.

Calculate the probability that the card chosen is labelled with a vowel or letter "R"

• 4/7

• 12/49

• 3/7

• 37/49

Two prefects are chosen at random from five prefects, where three of them are in Form Four and two are in Form Five.

Calculate the probability that both prefects chosen are in the same form.

• 0.09

• 0.6

• 0.10

• 0.4

The probability of Kam Seng passing his Physics and Chemistry tests are 0.58 and 0.42 respectively.

Calculate the probability that

a) Kam Seng passes both tests.

• 0.2345

• 0.2436

• 0.2433

• 0.2536