GRADE  9-12 / Age 14+

The Five Challenges

1.  I mistakenly divided a number by 5 when I should have multiplied it by 5.  Find my percent of error.

2.  If a is 50% larger than c and b is 25% larger than c, then a is what percent larger than b?

3.  A student has scored 84, 78, and 86 on 100-point examinations.  How many points does he or she need to score on the 200-point final examination to get an average of 90%, which is an A, in the course?

4.  If the chances of rain are 40% and 20% for the two days of a weekend, what is the chance that it will rain on at least one of the two days?

5.  Mr. Salas receives a 10% raise every year.  His salary after four such raises has gone up by what percent?

Be sure to use your MathWorld Interactive six problem-solving steps. Have fun!

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