(i)[3]
Show that, when exactly $3$ of the digits are used, $12$ different odd numbers can be made.
(ii)[3]
Work out how many odd numbers in total can be formed.
Mathematics 9709 · AS & A Level · Sampling and estimation
Sampling and estimation — practice question
The numbers may be made from any selection of the digits $4, 5, 6, 7$, using each digit at most once.
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Spot numbers ending in 5 or 7 and count the possible arrangements” …
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