In 1994 the life expectancy of males in a certain country was 72.7 years. In 2oo1, it was 74.8 years. Let E represent the expectancy in year T and let T represent the number of years since 1994. The linear function E (t) that fits the data is
2001-1994=7
74.8-72.7=2.1
2.1/7=0.3
E(t)=72.7+0.3*t