Question

the graph shows the percentage of high school seniors who used alcohol or marijuana during the 30 days prior to being surveyed. the data can be described by the following mathematical models, where n is the number of years after 1980, a is the percentage of seniors using alcohol, and m is the percentage of seniors using marijuana. a = - 0.8n + 69 m = - 0.6n + 35 a. use the appropriate line graph to determine the percentage of seniors who used marijuana in 1990. % (type a whole number.)

Explanation:

Step1: Calculate the value of n for 1990

Since n is the number of years after 1980, for 1990, $n = 1990 - 1980=10$.

Step2: Substitute n into the marijuana - use formula

The formula for the percentage of seniors using marijuana is $M=-0.6n + 35$. Substitute $n = 10$ into it: $M=-0.6\times10 + 35$.

Step3: Perform the arithmetic operation

First, calculate $-0.6\times10=-6$. Then, $M=-6 + 35=29$.

Answer:

29