Math Problems, Proportions Problems

Problem of the Day: 1/5/13

The Jones family wants to paint one of the bedrooms in the Jones house. The bedroom has 240 square feet of wall to be painted, after excluding doors and windows. Daddy Jones can paint 4 square feet in one minute, Mommy Jones can paint 5 square feet in two minutes, and Baby Jones can paint 3 square feet in two minutes. If all of them paint continuously together, how long will it take the Jones family to lay three coats of paint on the bedroom walls?

Solution to yesterday’s problem:
We know there are 50 coins, and 16 of them are green on both sides. That means that 34 of the coins are green on at most one side. We also know that 6 of the coins are not green on either side, which leaves 28 coins green on exactly one side. Since it is mentioned that the number with green heads and the number with green tails are equal, we know that 14 coins have a green head, and 14 have a green tail. The probability of picking a coin with green tails is \frac{14}{50}, or after reducing, \frac{7}{25}.

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s