Researchers at a university want to know if higher levels of nitrogen in fertilizer will increase the production of tomatoes per plant. twenty plants are given normal levels of nitrogen and twenty other plants are given ten percent higher levels throughout the growing season. the plants receive the same levels of sunlight, water and are planted in the same soil on one farm. at the end of the experiment the average number of tomatoes produced is the same for each group. the scientists repeat the experiment on two additional farms further south that season. the researchers conclude that increasing nitrogen levels by 10% in tomatoes is not beneficial. would this be a well-designed, reliable experiment? support your decision with at least three reasons.

Afixed electric space heater wired by a cable with an ampacity of 30 a should draw a maximum current of a. 30 a. b. 24 a. c. 15 a. d. 27 a.

Suppose water is leaking from a tank through a circular hole of area ah at its bottom. when water leaks through a hole, friction and contraction of the stream near the hole reduce the volume of water leaving the tank per second to cah 2gh , where c (0 < c < 1) is an empirical constant. a tank in the form of a right-circular cone standing on end, vertex down, is leaking water through a circular hole in its bottom. (assume the removed apex of the cone is of negligible height and volume.) (a) suppose the tank is 20 feet high and has radius 8 feet and the circular hole has radius 2 inches. the differential equation governing the height h in feet of water leaking from a tank after t seconds is dh dt = − 5 6h3/2 . if the height of the water is initially 8 feet, how long will it take the tank to empty? (round your answer to two decimal places.)

Considering only the earth's rotation, determine how much later the asteroid would have had to arrive to put the explosion above helsinki at longitude 25˚ e? this would have obliterated the city.