(a)[2]
Write the ratio walk : cycle : swim in its simplest form.
(b)[3]
Sophia walks with an average speed of $1.4\,\text{m s}^{-1}$. She finishes the walk at $11\,05$. Find the time she starts walking.
(c)[3]
Sophia cycles $3000\text{ m}$, correct to the nearest $10$ metres, in $450$ seconds, correct to the nearest $10$ seconds. Calculate the upper bound for her mean cycling speed in metres per second.