Foundation June 2024 Paper 3 Q27
27 Tim has two biased coins, coin A and coin B.
He is going to throw both coins.
The probability that coin A will land on heads is 0.6
The probability that coin B will land on heads is 0.55
(a) Complete the probability tree diagram.
Tim throws coin A once and he throws coin B once.
(b) Work out the probability that both coins land on heads. (2)
| Answer | Mark | Mark scheme |
|---|---|---|
| 0.4 0.45, 0.55, 0.45 | B1 | for 0.4 in correct position |
| B1 | for the correct probabilities for coin B in the correct place on the branches |
Additional guidance
Accept equivalent fractions or percentages for probabilities
| Answer | Mark | Mark scheme |
|---|---|---|
| 0.33 | M1 | for a correct method, eg \(0.6 \times 0.55\) only |
| A1 | for 0.33 oe |
Additional guidance
An answer of \(\dfrac{0.33}{1}\) scores M1A0