Answer
a. 4178 homicides of 15- to 19-year-olds in the U.S. in 1992.
b. 1019 homicides of 15- to 19-year-olds in the U.S. in 2002.
c. 1998.
Work Step by Step
a. $N=-315.9t + 4809.8$ with $t=2$
$N=-315.9(2) + 4809.8$
$N=-631.8 + 4809.8$
$N=4178$
b. $t=2002 - 1990$ so $t=12$
$N=-315.9(12) + 4809.8$
$N=-3790.8 + 4809.8$
$N=1019$
c. $N=7337$
$7337=315.9(t) + 4809.8$
$7337-4809.8=315.9(t)$
$2527.2=315.9(t)$
$2527.2\div315.9=t$
$t=8$
$1990 + 8 = 1998$
