Chapter 18, Problem 18.82P

DATA The statistical quantities “average value” and “root-mean-square value” can be applied to any distribution. Figure P18.82 shows the scores of a class of 150 students on a 100-point quiz. (a) Find the average score for the class. (b) Find the rms score for the class. (c) Which is higher: the average score or the rms score? Why?

Figure P18.82

altitude of about 11 km, the temperature is not uniform but decreases with increasing elevation. (a) Show that if the temperature variation is approximated by the linear relationship

$T=T_0-\alpha y$

where T₀ is the temperature at the earth’s surface and T temperature at height y, the pressure p at height y is

$\ln \left(\frac{p}{p_0}\right)=\frac{Mg}{R\alpha }\ln \left(\frac{T_0-\alpha y}{T_0}\right)$

where P₀ is the pressure at the earth’s surface and M is the molar mass for air. The coefficient α is called the lapse rate of temperature. It varies with atmospheric conditions, but an average value is about 0.6 C°/100 m. (b) Show that the above result reduces to the result of Example 18.4 (Section 18.1) in the limit that α → 0. (c) With α = 0 6 C°/100 m, calculate p for y = 8863 m and compare your answer to the result of Example 18.4. Take T₀ = 288 K and p₀ = 1.00 atm.