A bus travels 45 km in 1 hour 15 minutes. How much time is required to cover 210km?

$1 \mathrm{hour}=60 \mathrm{minutes}$

$1 \mathrm{hr} 15 \mathrm{mins}=60+15$

$=75 \mathrm{minutes}$

$\mathrm{Time} \mathrm{taken} \mathrm{to} \mathrm{cover} 45\mathrm{km}=1 \mathrm{hr} 15 \mathrm{mins}$

$\mathrm{Time} \mathrm{taken} \mathrm{to} \mathrm{cover} 1 \mathrm{km}=\frac{75}{45}$

$\mathrm{Time} \mathrm{taken} \mathrm{to} \mathrm{cover} 210 \mathrm{km}=210 \mathrm{x} \frac{75}{45}$

$=350 \mathrm{minutes}$

$350 \mathrm{minutes}=5 \mathrm{hr} 50 \mathrm{mins}$