Question

1.

a)If you were to toss a coin twice. What is the probability that it would come up Heads once and Tails once. Express you answer in decimals to one place.

b)The sum of the probability of all outcomes equals?  Express your answer as a percentage to one decimal place.

Answer 1

a)

If you were to toss a coin twice.

What is the probability that it would come up Heads once and Tails once

P[ Heads once and Tails once ] = P[ head in first trial ]*P[ tail in second trial ] + P[ tail in first trial ]*P[ head in second trial ]

P[ Heads once and Tails once ] = 0.5*0.5 + 0.5*0.5 = 0.25 + 0.25 = 0.5

( 2 options heads and tails with equal probability )

b)The sum of the probability of all outcomes equals?  Express your answer as a percentage to one decimal place.

All possible outcome are :

0 heads and 2 tails

2 heads and 0 tails

Heads once and Tails once

P[ Heads once and Tails once ] = 0.5

P[ 0 heads and 2 tails ] = P[ head in first trial ]*P[ tail in second trial ] = 0.5*0.5 = 0.25

P[ 2 heads and 0 tails ] = P[ head in first trial ]*P[ head in second trial ] = 0.5*0.5 = 0.25

sum of probability of all outcome = 0.5 + 0.25 + 0.25 = 1

In terms of %, sum of probability of all outcome = 100%