Find his velocity when $t = 15$.

Calculate the vertical distance Xavier travelled in the first 10 seconds.

Determine the value of $h$.

$v(15) = \frac{{98}}{{\sqrt {1 + {{(15 - 10)}^2}} }}$     (M1)

$v(15) = 19.2{\text{ }}({\text{m}}{{\text{s}}^{ - 1}})$     A1

[2 marks]

$\int\limits_0^{10} {9.8t\,{\text{d}}t}$    (M1)

$= 490{\text{ }}({\text{m}})$     A1

[2 marks]

$\frac{{98}}{{\sqrt {1 + {{(t - 10)}^2}} }} = 2.8$     (M1)

$t = 44.985 \ldots {\text{ }}({\text{s}})$     A1

$h = 490 + \int\limits_{10}^{44.9...} {\frac{{98}}{{\sqrt {1 + {{(t - 10)}^2}} }}{\text{d}}t}$    (M1)(A1)

$h = 906{\text{ (m}})$     A1

[5 marks]