Question

Find the cardinal number of the following sets.

(i) M = {p, q, r, s, t, u}

(ii) P = {x : x = 3n + 2, n∈W and x < 15}

(iii) Q = { y : y = 4/3n, n ∈ N and 2 < n ≤ 5}

(iv) R = {x : x is an integers, x ∈ Z and –5 ≤ x < 5}

Answer 1

i. Clearly n(M) = 6

ii. P = { 2, 5 , 8, 11, 14 }
since P contains 5 elements n(P) = 5

iii. Q = {243, 768, 1875 }
since Q contains 3 elements n(Q) = 3

iv. R = { -5, -4, -3, -2, -1, 0, 1, 2, 3, 4}
since R contains 10 elements n(R) = 10

v. S = { 1884, 1888, 1892, 1896, 1904}
since S contains 5 elements n(S) = 5