Foundation November 2024 Paper 2 Q20
20 Beth and Lynn each spin the same biased coin a number of times.
The table shows information about the results.
| Beth | Lynn | |
|---|---|---|
| Number of spins | 125 | 80 |
| Relative frequency of Heads | 0.32 | 0.35 |
(a) How many more Heads did Beth spin than Lynn? [2 marks]
(b) Lynn says,
“My estimate of the probability of the coin landing on Heads must be the best, because 0.35 is greater than 0.32”
Is she correct?
Tick a box.
- Yes
- No
Give a reason for your answer. [1 mark]
| Answer | Mark | Comments |
|---|---|---|
| \(125 \times 0.32\) or 40 or \(80 \times 0.35\) or 28 | M1 | oe |
| 12 | A1 |
Additional guidance
| M1 may be awarded for correct work with no answer or incorrect answer, even if this is seen amongst multiple attempts | |
| \(80 \times 0.5 = 40\) | M0 |
| Answer | Mark | Comments |
|---|---|---|
| No and valid reason involving the number of trials | B1 | eg reasons she didn’t do the most she did fewer spins Beth did more they should use all 205 spins |
Additional guidance
| Ignore irrelevant or incorrect statements alongside a correct statement as long as not contradictory eg1 No and Beth did most but she could have done more eg2 No and Beth has more number of spins so there is a higher probability of landing on heads eg3 No and Beth did most spins but Lynn did more | B1 B1 B0 |
| Allow ‘she’ to refer to Lynn unless clearly referring to Beth eg No and Because she tried 125 times however Lynn tried only 80 times | B1 |
| No and She did not do as many spins so her answer is less accurate than Beth’s | B1 |
| No and Beth spun the wheel more times. Therefore her probability would be lower | B1 |
| No and Beth spun more times so her final outcome will be higher | B1 |
| No and Beth did 125 spins and Lynn did 80 spins | B0 |
| No and Beth did 125 spins so she has more chance of being accurate | B0 |