A tank initially holds 100 gallons of salt solution in which 50 lbs of salt has been dissolved. A pipe fills the tank with brine at the rate of 3 gpm, containing 2 lbs of dissolved salt per gallon. Assuming that the mixture is kept uniform by stirring, a drain pipe draws out of the tank the mixture at 2 gpm. Find the amount of salt in the tank at the end of 30 minutes.

Luminous objects such as flashlights emit light that we can see. how do we see an object that isn’t luminous? a. the object emits light that reaches our eyes. b. light reflects off the object and reaches our eyes. c. light passes through the object uninterrupted. d. light is fully absorbed by the object. e. we can’t see an object that isn’t luminous.

When you look at the data about all of the children in your setting, you can learn a. about child development. b. how well each individual child is performing. c. what outside factors you need to change. d. how effective your instruction and environment are.

Nathan is an ecologist. he’s studying the effect of secondary consumers on primary consumers. his current research focuses on a population of blue jays and crows. they eat caterpillars and mice. if the number of blue jays increases, what are the likely effects on other populations? 1the number of crows will increase. 2the number of mice will decrease. 3the number of mice will remain the same. 4the number of caterpillars will decrease.