Jo likes to watch videos. Sometimes she watches them at normal speed. However, she also has the option to watch them at \(\frac{1}{4}\) as fast as normal speed, \(\frac{1}{2}\) as fast as normal speed, or \(2\) times as fast as normal speed. The table below lists the normal play times for four videos and the speed at which Jo watches each one.
| Normal Speed Time | Speed Jo Watches Video At | |
|---|---|---|
| Video A | \(50\) seconds | \(\frac{1}{4}\) speed |
| Video B | \(2\) minutes \(15\) seconds | normal speed |
| Video C | \(1\) minute \(40\) seconds | \(\frac{1}{2}\) speed |
| Video D | \(6\) minutes \(20\) seconds | \(2\) times speed |
What is the total time Jo spent watching these four videos?
If a video is playing at \(\frac{1}{4}\) speed, then it will take \(4\) times as long to play as normal speed. So a \(50\) second video will take \(50 \times 4 = 200\) seconds to watch.
If a video is playing at \(\frac{1}{2}\) speed, then it will take \(2\) times as long to play as normal speed. So a \(1\) minute and \(40\) second video will take \(2\) minutes and \(40 \times 2 = 80\) seconds to watch.
If a video is playing at \(2\) times speed then it will take half as long to play as normal speed. Half of \(6\) minutes is \(3\) minutes and half of \(20\) seconds is \(10\) seconds.
Now we can add up all the minutes and seconds of playing times of all four videos: \[2 + 2 + 3 = 7~\text{minutes and }200 + 15 + 80 + 10 = 305~\text{seconds}\]
There are \(60\) seconds in \(1\) minute. When we skip count by \(60\), we get \(60\), \(120\), \(180\), \(240\), \(300\). Thus, there are \(5\) minutes in \(305\) seconds with \(305 - 300 = 5\) seconds left over.
So Jo spent \(7 + 5 = 12\) minutes and \(5\) seconds watching these four videos.