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Flying against the wind, an airplane travels 6860 kilometers in 7 hours. Flying with the wind, the same plane travels 7800 kilometers in 6 hours. What is the rate of the plane in still air and what is the rate of the wind?

\begin{tabular}{|c|c|}
\hline
Rate of the plane & [tex]$\square \frac{\text{km}}{\text{h}}$[/tex] \\
\hline
Rate of the wind & [tex]$\square \frac{\text{km}}{\text{h}}$[/tex] \\
\hline
\end{tabular}


Sagot :

Let's solve the problem step-by-step.

1. Define the given information:
- Distance traveled against the wind: 6860 km
- Time taken to travel against the wind: 7 hours
- Distance traveled with the wind: 7800 km
- Time taken to travel with the wind: 6 hours

2. Calculate the speed of the airplane against the wind:
We know that speed is distance divided by time. Therefore,
[tex]\[ \text{Speed against the wind} = \frac{\text{Distance against the wind}}{\text{Time against the wind}} = \frac{6860 \text{ km}}{7 \text{ hours}} = 980 \text{ km/h} \][/tex]

3. Calculate the speed of the airplane with the wind:
Using the same speed formula,
[tex]\[ \text{Speed with the wind} = \frac{\text{Distance with the wind}}{\text{Time with the wind}} = \frac{7800 \text{ km}}{6 \text{ hours}} = 1300 \text{ km/h} \][/tex]

4. Formulate the equations:
- Let \( p \) be the rate of the plane in still air (plane speed).
- Let \( w \) be the rate of the wind speed.

When flying against the wind:
[tex]\[ p - w = 980 \text{ km/h} \][/tex]

When flying with the wind:
[tex]\[ p + w = 1300 \text{ km/h} \][/tex]

5. Solve the system of equations:
- Add the two equations:
[tex]\[ (p - w) + (p + w) = 980 + 1300 \][/tex]
[tex]\[ 2p = 2280 \][/tex]
[tex]\[ p = \frac{2280}{2} = 1140 \text{ km/h} \][/tex]

- Subtract the first equation from the second:
[tex]\[ (p + w) - (p - w) = 1300 - 980 \][/tex]
[tex]\[ 2w = 320 \][/tex]
[tex]\[ w = \frac{320}{2} = 160 \text{ km/h} \][/tex]

6. Conclusion:
- The rate of the plane in still air: \( 1140 \text{ km/h} \)
- The rate of the wind: \( 160 \text{ km/h} \)

Therefore,
[tex]\[ \begin{array}{|c|c|} \hline \text{Rate of the plane:} & 1140 \frac{\text{ km }}{\text{ h }} \\ \hline \text{Rate of the wind:} & 160 \frac{\text{ km }}{\text{ h }} \\ \hline \end{array} \][/tex]