Given,

Mean $(m) =68$

Standard deviation $(S.D.) =4$

Total no. of students $(n) =500$.

$$z=\dfrac {X-m}{\sigma}=\dfrac{X-68}4$$

(i) Now to evaluate no. of students less than 62 inches i.e. from 0 to 62

When $x=62 ,z=(62-68)/4\\ Z=-6/4 \\ Z=-1.5$

When $x=0, z=(0-68)/4=-17$

$\therefore P(-17 \lt z \lt -1.5) =$ Area from (z=0 to -17)-Area from (z=0 to -1.5)

$=0.499-0.433 \\ =0.0657$$

Note: Evaluating integration on calc.

$\Bigg[\dfrac 1{\sqrt{2\pi}}\int\limits_0^{-1.5}C^{\frac {-1}2z^2}dz\Bigg]$

Probability of students having height less than 62 inches is $0.0657$

$\therefore B=P \times N \\ \therefore B=0.0657 \times 300 $

$\therefore B=33 $students.

(ii) Question is not clear.