Question

In Danny's class, the number of boys is $17$ more than the number of girls. Which of the following can not be the number of boys in the class?

• A. $18$
• B. $17$
• C. $16$

Answer 1

The correct option is C $16$

Let the number of girls in the class be $x$
Accordingly, the number of boys in the class is $x+17$

Option A: If the number of boys in the class is $18$
$\Rightarrow x+17=18$
$\Rightarrow x+17-17=18-17$
$\Rightarrow x=1\to$ only one girl in the class.
So, number of boys can be $18$ in the class.

Option B: If the number of boys in the class is $17$
$\Rightarrow x+17=17$
$\Rightarrow x+17-17=17-17$
$\Rightarrow x=0\to$ No girl in the class.
So, number of boys can be $17$ in the class.

Option C: If the number of boys in the class is $16$
$\Rightarrow x+17=16$
$\Rightarrow x+17-17=16-17$
$\Rightarrow x=-1\to$ the number of girl can't be $-1$.
​​​​​​​So, number of boys can not be $16$ in the class.