Question 1101424
the equation is R = -.075 * T + 3.85


you want to know when R will be less than 3.7.


since R = -.075 * T + 3.85, then R < 3.7 when -.075 * T + 3.85 < 3.7


your inequality to solve is -.075 * T + 3.85 < 3.7


add .075 * T to both sides of this inequality and subtract 3.7 from both sides of this inequality to get:


3.85 - 3.7 < .075 * T


combine like terms to get:


.15 < .075 * T


divide both sides of this inequality by .075 to get:


.15 / .075 < T


solve for T to get T > .15 / .075 which results in T > 2


when T is greater than 2. the year is greater than 1930 + 2 = 1932.


the world record in the 1500 meter run will be less than 3.7 minutes after 1932.


R = -.0675 * T + 3.85 for T from 0 to 3 results in:


R = 0.0675 * 0 + 3.85 = 3.85 in 1930.
R = -.0675 * 1 + 3.85 = 3.7825 in 1931.
R = -.0675 * 2 + 3.85 = 1.7125 in 1932.
R = -.0675 * 3 + 3.85 = 3.6475 in 1933.