# Tutor profile: Doug G.

## Questions

### Subject: Pre-Algebra

You have several coins in a sack. There are three times as many quarters as dimes and four times as many dimes as nickels. What is the probability that Jair will take a dime out if he does so without looking?

Since there are 3 times as many quarters as dimes and 4 times as many dimes as nickels, there are 3x4=12 times as many quarters as nickels. The ratio of nickels to dimes to quarters is 1:4:12. If there is one nickel, there are 4 dimes and 12 quarters, for a total of 17 coins. Since there are 4 dimes, the probability of drawing one is 4/17.

### Subject: Basic Math

You got a new puppy! The puppy food says to feed her 1/3 cup twice a day. You're going on vacation for two days. How much food will you need to bring?

If you feed her 1/3 cup twice a day, then in one day you will feed her 1/3 + 1/3 = 2/3 cup. For two days, you will need 2/3 + 2/3 = 4/3. To change 4/3 to a proper fraction, divide. 3 goes into 4 once, with one left over. You will need 1 1/3 cups. Of course, you may want to bring a little extra just in case you spill some.

### Subject: Algebra

You have $45 saved up so far for the new iPhone, which will cost $599 (which includes tax). You make $10/hour cutting grass, $8/hour to babysit your neighbor and $10/week to walk your other neighbor's dog. You cut two lawns per week; one takes 45 minutes and the other takes 1 1/2 hours. You only babysit once a week, for 3 hours. How long until you've saved enough for the iPhone?

Since you already have $45, you need 599-45 = $554. You cut grass for 3/4 hour (45 minutes) plus 1 1/2 hours = 2 1/4 hours per week. $10/hour times 2 1/4 hours is $22.50 per week. You babysit 3 hours per week at $8/hour, so you make 3x8=$24 per week. Altogether, you make $22.50+$24+$10= $56.50/week. $554 divided by $56.50 is 9.8 weeks. You will have enough to purchase the phone after 10 weeks.

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