The carbon dioxide concentration in the atmosphere was 282 parts per million (ppm) in the year 1750. In the year 2010, this increased to 387 ppm. Calculate the percentage increase in carbon dioxide concentration over this period of time. Round your answer to the nearest whole number.

Astudent pours 10.0 g of salt into a container of water and observes the amount of time it takes for the salt to dissolve. she then repeats the process using the same amounts of salt and water but this time she slowly stirs the mixture while it is dissolving. the student performs the experiment one more time but this time she stirs the mixture rapidly. the dependent variable in this experiment is: time for salt to dissolve speed of stirring amount of water mass of salt