The median of the numbers on his four cards is 7.5.
What number is on the fourth card?
The mean of the numbers on these three cards is 8.
Ava selects a fourth card.
The mean of the numbers on her four cards is 9.5.
What number is on the fourth card? [4 marks]
Worked Solution & Mark Scheme (6 marks)
For 4 cards with median 7.5, the sum of the two middle cards must be 7.5 × 2 = 15
Middle cards are 6 and the fourth card: 6 + x = 15 ⇒ x = 9
Ordered: 3, 6, 9, 11
median = (6 + 9)/2 = 7.5. A1
Total of 4 cards = 4 × 9.5 = 38 M1
Fourth card = 38 - 24 = 14. A1