2024 Author: Malcolm Clapton | [email protected]. Last modified: 2023-12-17 03:44
Help your grandson figure out what time the walk will take place.
A grandson approaches grandfather Semyon, a retired mathematics teacher, and asks:
- Grandfather, tell me, what time is it?
- Add ¼ of the time elapsed from midnight to now, from ½ from now to midnight.
- Oh! Seems to understand. When will we go outside?
- Add to the received time 10 minutes, then let's go.
What time is it and what time are these two going for a walk?
There are 24 hours a day. Let x time have passed from midnight to now, then from now to midnight there are 24 times left. If you add a quarter of the time from midnight to now and half of the time from now to midnight, you get x, the current time. Let's write it down with an equation and solve it:
¼ × x + ½ × (24 - x) = x
x / 4 + 12 - x / 2 = x
x - x / 4 + x / 2 = 12
4x - x + 2x = 48
5x = 48
x = 9.6
It turns out that 9, 6 hours, or 9 hours 36 minutes have passed from midnight to now, this is the current time. And grandfather and grandson will go for a walk in 10 minutes, that is, at 9 hours 46 minutes.
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