Page 310 - Start Up Mathematics_7

5. A drawer contains 4 black socks, 6 brown socks and 2 red socks. Suppose one sock is drawn

from the drawer and the event of drawing a sock is equally likely. Find:
(a) P (the sock is black)

(b) P (the sock is either black or red)

(c) P (the sock is green)

(d) P (the sock is not green)
6. A roulette wheel has 36 slots around the rim. The first 32 slots are numbered from 1 to 32.

Half of these 32 slots are green and the other half are yellow. The remaining 4 slots have
jackpot, bumper, try again and penalty inscribed on them. A small ivory ball spun in the
direction opposite to that of the wheel has equal chances of falling in any one of the 36 slots.
Find each of the following:

(a) The probability that the ball lands in a yellow slot

(b) The probability that the ball lands in a jackpot

(c) The probability that the ball does not land on a numbered slot
(d) The probability that the ball lands on an odd numbered slot

Thinking Skills

1. In the adjacent spinner colour the sectors such that:

(a) probability of red is 0.3 (b) probability of blue is 0.4

(c) probability of green is 0.1 (d) probability of yellow is 0.2

2. Write each letter in the word ‘ASSASSINATION’ on a separate chit of
paper and put them in a bag. Without looking, take out one chit at random. Find each of the
following:

(a) P (selecting A) (b) P (selecting S) (c) P (selecting a vowel)

(d) P (selecting T) (e) P (choosing any letter) (f) P (choosing Z)

3. A coin is tossed and it lands anywhere within the region with equal likelihood. Find the
probability that the coin will land on the shaded region. (These figures are not drawn to scale.)

(a) 3 m (b) (c) (d)
1 m

4. What will be the probability in each part of the above question (i.e., Q. 3), if we want the
coin to land in the shaded region with head on top?

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