(b) How many grey tiles are needed for Pattern number 10? (2)
Jenny says,
‘I will need exactly 46 grey tiles for Pattern number 18’.
(c) Is Jenny right? You must give a reason for your answer. (2)
Mark scheme (a)
Answer
Mark
Notes
1
B1 for correct pattern
Mark scheme (b)
Answer
Mark
Notes
31
2
M1 for correct diagram of pattern number 10 with or without shading A1 cao OR M1 for any 4 consecutive terms in the sequence 4, 7, 10, .... A1 cao OR M1 for use of \(3n + 1\) with \(n = 10\) A1 cao
Mark scheme (c)
Answer
Mark
Notes
No with appropriate reason
2
M1 for attempt to divide 45 by 3 A1 for ‘No’ and comment that this is the number needed for pattern number 15 OR M1 for starts at 4 and builds up correctly to 46 or 55 A1 for ‘No’ and comments that 55 are needed for pattern 18 or 46 are needed for pattern 15 oe OR M1 for use of \(3n + 1\) with \(n = 18\) A1 for ‘No’ and comments that 55 are needed for pattern 18 oe OR M1 for \(3n + 1 = 46\) A1 for ‘No’ and comments 46 are needed for pattern 15 oe
