maximum heart rate for various ages. For this problem, use this model:  M=208−0.74⋅AM=208-0.74⋅A  M = Maximum Heart Rate in beats per minute A = age Q. For what age would the maximum heart rate be 168 bpm (assuming this equation applies at that time)?

At what speed should a fish swim upstream so as to reach its destination with the least expenditure of energy? The energy depends on the friction of the fish through the water and on the duration of the trip. If the fish swims with velocity v, the energy has been found experimentally to be proportional to (for constant k > 2) times the duration of the trip. A distance of s miles against a current of speed c requires time -c (distance divided by speed). The energy required is then proportional to k = 3, minimizing energy is equivalent to minimizing |- v³ E(v) = = V C vk s v-c. For Find the speed v with which the fish should swim in order to minimize its expenditure E(v). (Your answer will depend on c, the speed of the current.)

While the rate at which ethanol can be produced is important, the total quantity of ethanol that can be produced from a given crop is also important. Use the information listed below to calculate the theoretical yield of ethanol from a 1 hectare plot of corn and a 1 hectare plot of sugarcane in the U.S. (1 hectare = 2 football fields). Show your calculations. Corn Yield: 138 bushels of seed per hectare 1 bushel seed = 2.8 gallons ethanol Sugarcane Yield: 89 tons sugarcane per hectare 1 ton sugarcane = 19.5 gallons ethanol

The air in a room 15 ft by 12 ft by 12 ft is 4% carbon monoxide. Starting at t = 0, fresh air containing no carbon monoxide is blown into the room at a rate of 300 ft³/min. If air in the room flows out through a vent at the same rate, when will the air in the room be 0.01% carbon monoxide? The air in the room will be 0.01% carbon monoxide after (Round to two decimal places as needed.) minutes.