During the war, the same arms merchant often sells weapons to both sides of the conflict. in this situation, a different price could be offered to each side because there is no danger of resale. suppose a us arms merchant has a monopoly of a special air-to-sea missiles and is willing to sell them to both india and china. india's demand for missiles is p = 64 - 4x and china's is p = 80 - 6y, where p is in millions of dollars. the marginal cost of missiles is mc = 4q, where q = x + y. (a) how many missiles will be sold to each country and what price will be charged to each country? show your work in details. (b) find out the price elasticity of demand for each country at that price and check that the country with less elastic demand is indeed paying a higher price.

Reliability and validity reliability and validity are two important considerations that must be made with any type of data collection. reliability refers to the ability to consistently produce a given result. in the context of psychological research, this would mean that any instruments or tools used to collect data do so in consistent, reproducible ways. unfortunately, being consistent in measurement does not necessarily mean that you have measured something correctly. to illustrate this concept, consider a kitchen scale that would be used to measure the weight of cereal that you eat in the morning. if the scale is not properly calibrated, it may consistently under- or overestimate the amount of cereal that’s being measured. while the scale is highly reliable in producing consistent results (e.g., the same amount of cereal poured onto the scale produces the same reading each time), those results are incorrect. this is where validity comes into play. validity refers to the extent to which a given instrument or tool accurately measures what it’s supposed to measure. while any valid measure is by necessity reliable, the reverse is not necessarily true. researchers strive to use instruments that are both highly reliable and valid.