A company determines that the revenue, in dollars, for selling a particular model of lamp is given by
R(x) = x(–20x + 1200), where x is the price of
each lamp. At which of the following prices will the
company's revenue be $10,000 ?

Arandom sample of n = 25 observations is taken from a n(µ, σ ) population. a 95% confidence interval for µ was calculated to be (42.16, 57.84). the researcher feels that this interval is too wide. you want to reduce the interval to a width at most 12 units. a) for a confidence level of 95%, calculate the smallest sample size needed. b) for a sample size fixed at n = 25, calculate the largest confidence level 100(1 − α)% needed.