Speed problems: The Speed Table - Handling Speed Problems with Data Overload
Tom drives from town _A_ to town _B_, driving at a constant speed of 60 miles per hour. From town _B_, Tom immediately continues to town _C_. The distance between _A_ and _B_ is twice the distance between _B_ and _C_. If the average speed of the whole journey was 36 mph, then what is Tom's speed driving from _B_ to _C_ in miles per hour?
Incorrect.
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Incorrect.
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Incorrect.
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Incorrect.
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Now fill in the missing entries you can easily calculate. Notice that you can fill in the entries in the Time column:
| | SPEED (MPH) | TIME (H) | DISTANCE (MILES) |
|-------------------|-------------------------------------|-------------------------------|------------------------------|
| _A_ $$\rightarrow$$ _B_ | $$60$$ | $$\color{green}{\frac{60}{60} = 1}$$ | $$60$$ |
| _B_ $$\rightarrow$$ _C_ | $$\color{red}{?}$$ | $$\color{purple}{2.5-1= 1.5}$$ | $$30$$ |
| | $$\text{Average} = 36$$ | $$\color{green}{\frac{90}{36}=2.5}$$ | $$\text{Total} = 90$$ |
Finally, calculate the average speed from _B_ to _C_ by dividing distance by time:
>$$\displaystyle \text{Speed} = \frac{30\ \text{miles}}{1.5\ \text{hour}}=20\ \text{mph}$$
Correct.
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This is how the Speed table looks if you __Plug In__ 30 miles for the _B_ $$\rightarrow$$ _C_ distance.
| | SPEED (MPH) | TIME (H) | DISTANCE (MILES) |
|-------------------|-------------------------|----------|------------------------------|
| _A_ $$\rightarrow$$ _B_ | $$60$$ | | {color:dark-blue}$$60$${/color} |
| _B_ $$\rightarrow$$ _C_ | $$\color{red}{?}$$ | | {color:dark-blue}$$30$${/color} |
| | $$\text{Average} = 36$$ | | $$\text{Total} = 90$$ |
The last row is used for summing up the times and distances and for finding the average speed.
12
20
24
30
36
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