Answer
n(B) = 7
Work Step by Step
Given B={x|x belongs to N where 3 $\leq$ x <10}
From the given question.
The given set represents the natural numbers which are greater than equal to 3 but less than 10
Those numbers are 3,4,5,6,7,8,9.
The set contains 7 elements.
The cardinal number for each set is formed by calculating the number of elements in each set.
Therefore the cardinal number for given set B is n(B) = 7.
