Question

of the last 20 trains to arrive at Lansbury station 18 were on time considering this data how many of the next 10 trains would you expect to be on time

Answer 1

$\bf \begin{array}{ccll} arriving&on~time\\ \text{\textemdash\textemdash\textemdash}&\text{\textemdash\textemdash\textemdash}\\ 20&18\\ 10&x \end{array}\implies \cfrac{20}{10}=\cfrac{18}{x}\implies x=\cfrac{10\cdot 18}{20}$