2. The cost of one ruler is r cents The cost of one protractor is
P
cents
The lotal cost of 5 rulers and 1 protractor is 25 pus cents
The total cost of 2 rulers and 3 protractors is 215 cents
Write down two equations in terms of r and
Р
and solve
these equations to find the cost of one protractor

Ur environment is very sensitive to the amount of ozone in the upper atmosphere. the level of ozone normally found is 4.04.0 parts/million (ppm). a researcher believes that the current ozone level is not at a normal level. the mean of 2525 samples is 4.44.4 ppm with a standard deviation of 0.80.8. assume the population is normally distributed. a level of significance of 0.020.02 will be used. make the decision to reject or fail to reject the null hypothesis. answer tables