Question

The set builder form of "A is the set of whole numbers which are divisible by 5 and are less than 35" is _______________.

• A. A = {$x:x=5n,n<7$}
• B. A = {$x:x=5n,n\in W,n\le 7$}
• C. A = {$x:x=5n,n\in W,n<7$}
• D. A = {$x:x=5n,n\in W$}

Answer 1

The correct option is C

A = {$x:x=5n,n\in W,n<7$}

$5n$ is a number which will be a multiple of 5, where $n$ is a whole number.
If $n$ = 7, then $5n$ = 35 which is not less than 35.
$\therefore$ A = {$x:x=5n,n\in W,n<7$}