Question

Flying against the wind a jet travels 7740 miles in 9 hours. Flying with the wind the same jet travels 4000 80 miles in 3 hours. What is the rate of the jet in still air and what is the rate of the wind?

Answer 1

`j\ \rightarrow\ the\ rate\ of\ the\ jet\ in\ still\ air \\w\ \rightarrow\ the\ rate\ of\ the\ wind\\\\j-w= \frac{\big{7740\ miles}}{\big{9\ hours}}\ \ \ \Rightarrow\ \ \ j-w=860\ (miles)/( hour)\\\\ j+w= \frac{\big{4080\ miles}}{\big{3\ hours}}\ \ \ \Rightarrow\ \ \ j+w=1360\ (miles)/( hour)\\----------\\\\2j=(860+1360)\ (miles)/( hour)\ \ \ \Rightarrow\ \ \ 2j=2220\ (miles)/( hour)\ \ \ \Rightarrow\ \ \ j=1110\ (miles)/( hour)`


`j+w=1360\ (miles)/( hour)\ \ \ \Rightarrow\ \ \ w=(1360}-1110)\ (miles)/( hour)=250\ (miles)/( hour)\\\\\\Ans.\ the\ rate\ of\ the\ jet\ in\ still\ air\ is\ 1110\ (mi)/(hr) \ \ \ \\\\.\ \ \ \ \ \ and\ \ \ the\ rate\ of\ wind\ is\ 250\ (mi)/(hr)`