Questions

[papergangsta]

Betty Luzes flips two fair coins and rolls a fair six-sided die. What are the odds that she will get at least one tail and a composite number?

Les Speed leaves El Paso on Interstate 10 and drives 90 kilometers per hour. Forty-five minutes later, Ima Speedstur leaves El Paso on Interstate 10 and drives 130 kilometers per hour. How long will it take for Ima to catch Les?

It takes 5 hours for 6 painters to paint 4 cars. How long would it take 15 painters to paint 14 cars?

A chemist has 3 quarts of 3% boric acid. How much of a 10% solution of the acid must he add to have a 4% solution?

[bradp]

Betty Luzes flips two fair coins and rolls a fair six-sided die. What are the odds that she will get at least one tail and a composite number?
Possible coin flip configurations:
HH TT HT TH - 3/4 have at least one tail
4 and 6 are composite numbers --> 1/3
3/4*1/3 = 1/4 probability, 1/3 odds. I hope this is right...

Les Speed leaves El Paso on Interstate 10 and drives 90 kilometers per hour. Forty-five minutes later, Ima Speedstur leaves El Paso on Interstate 10 and drives 130 kilometers per hour. How long will it take for Ima to catch Les?
Set up distance functions for each car, find their point of intersection

It takes 5 hours for 6 painters to paint 4 cars. How long would it take 15 painters to paint 14 cars?

4/(5*6) = cars painted per hour per painter.

A chemist has 3 quarts of 3% boric acid. How much of a 10% solution of the acid must he add to have a 4% solution?

mass balance on the boric acid
mass of boric acid in in original solution + mass of boric acid added = total mass of boric acid at the end
Concentrations of original, added, and end solutions are given in the problem.
3% * V_1 + 10% * V_add = 4% * (V_1+V_add)