The power, P(watts), of a car engine is proportional to the square of its speed, s(m/s). When s=45 P=2200.
Work out the speed (to 1 DP) when the power is 1890 watts

Recall that the owner of a local health food store recently started a new ad campaign to attract more business and wants to know if average daily sales have increased. historically average daily sales were approximately $2,700. the upper bound of the 95% range of likely sample means for this one-sided test is approximately $2,843.44. if the owner took a random sample of forty-five days and found that daily average sales were now $2,984, what can she conclude at the 95% confidence level?