Question
A new village social club has 10 members of whom 6 are men and 4 are women. The club committee will consist of 5 members.
(a) In how many ways can the committee of 5 members be chosen if it must include at least 2 men and at least 1 woman? [4]
The 10 members of the club stand in a line for a photograph.
(b) How many different arrangements are there of the 10 members if all the men stand together and all the women stand together? [2]
For a second photograph, the members stand in two rows, with 6 on the back row and 4 on the front row. Olly and his sister Petra are two of the members of the club.
(c) How many different arrangements are there of the 10 members in which Olly and Petra stand next to each other on the front row? [4]
Additional page
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Mark scheme
6(a) 4M 1W: 6 C4 × 4 C1 = 60 M1 6C
a × Cb with a + b = 5 seen, no extra terms.
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3M 2W: 6 C3 × 4 C2 = 120 B1 Correct outcome/value for one clearly identified scenario.
Accept unsimplified, www.
2M 3W: 6 C2 × 4 C3 = 60 Condone use of × 5 C0 .
M1 Add values of three correct scenarios, no incorrect scenarios,
no repeated scenarios.
Condone 6 Ca × 4 Cb with a + b = 5 to identify M, W for this
mark.
Total 240 A1 Not dependent on B1.
If A0 scored, SC B1 for 240 www.
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6(b) 6! × 4! × 2 M1 6! × 4! × k; k = 1, 2. 1 can be implied.
= 34 560 A1 Cao.
If M0 scored, SC B1 for 34 560 www.
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6(c) Method 1 – Arrangements of OP in front row, 8 remaining people arranged.
8! × 3 × 2 M1 8! × g, g an integer greater than 1.
M1 h! × 3 × j; h = 7, 8, 9; j = 1, 2 (1 may be implied).
Condone 3 C1 for 3.
M1 h! × 3 × 2; h = 7, 8, 9.
Condone 2 C1 for 2.
(Condone h! × 3! For M1M1).
= 241 920 A1 If A0 Scored, SC B1 for 241 920.
Method 2 – Two additional people selected for front row, front row arranged, remaining 6 people arranged in back row.
8 C × 6! × 3! × 2 M1 8 C × d, a = 2,6, d an integer greater than 1.
2 a
M1 6! × e, e an integer greater than 1.
M1 8 C × f ! × 3! × 2 or 8 C × f ! × 6 × 2; a = 2, 6; f = 5, 6, 7.
a a
= 241 920 A1 If A0 Scored, SCB1 for 241 920.
Method 3 – Arrangements of two additional people for front row, front row arranged, remaining 6 people arranged in back row.
8P 8P
2 × 6! × 3! M1 2 × d, d an integer greater than 1.
M1 6! × e, e an integer greater than 1.
M1 8P 8P
2 × h! × 3! or 2 × h! × 6; h = 5, 6, 7.
= 241 920 A1 If A0 Scored, SC B1 for 241 920.
6(c) Method 4 – Arrangements of 6 people for back row, front row arranged.
8P 8P
6 × 3! × 2! M1 6 × d, d an integer greater than 1.
M1 3! × e, e an integer greater than 1.
M1 8P
6 × j! × 2; j = 1, 2, 3.
= 241 920 A1 If A0 Scored, SC B1 for 241 920.
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