Question

Find the cardinal number of the set:

Answer 1

Answer: 6

Step-by-step explanation:

Ok lemme actually format this set

$C = \left\{\frac 1x : x \in \mathbb{Z}\ \text{and}\ 4 \leq x \leq 9\right\}$

Well the only integers from 4 to 9 are 4, 5, 6, 7, 8, 9. So this set is just

$C = \left\{\frac 14, \frac 15, \frac 16, \frac 17, \frac 18, \frac 19\right\}$

which has cardinality $\boxed{6}$ .