ECZ 2020 · GCE Paper 2 · Question 1 — Matrices

Question from ECZ 2020 · GCE Paper 2 · Question 1

(a) Given that matrix A = 74p95p,

(a(i)) find the value of p for which the determinant of A is -2,[2]

Verified working — step 1

det A = (7)(5p) - (4p)(9) = 35p - 36p = -p

(a(ii)) hence, find the inverse of A.[2]

Verified working — step 1

With p = 2: A = 78910 and det A = -2.

(b) Mutola and Mwambi were to be selected as members of a netball team. The probability of selecting Mutola is 78 and that of selecting Mwambi is 910. Find the probability that

(b(i)) only one of them is selected,[3]

Verified working — step 1

"Only one selected" is Mutola-yes-Mwambi-no or Mutola-no-Mwambi-yes:

(b(ii)) none of them is selected.[2]

Verified working — step 1

"None selected" is Mutola-not …

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Original examination question © Examinations Council of Zambia. Worked solution and commentary © G12 Titan — not to be reproduced without permission.

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