Amixture of pulverized fuel ash and portland cement to be used for grouting should have a compressive strength of more than 1300 kn/m2. the mixture will not be used unless experimental evidence indicates conclusively that the strength specification has been met. suppose compressive strength for specimens of this mixture is normally distributed with σ = 64. let μ denote the true average compressive strength.

Light from a sodium lamp passes through a diffraction grating that has 1000 slits per millimeter. the interference pattern is viewed on a screen 1.000 m behind the grating. the first (m = 1) two bright yellow fringes that are visible are 0.7288 m and 0.7300 m from the central maximum. what are the wavelengths of these two fringes?

What can you increase the strength of an electromagnet by

On a mild saturday morning while people are working inside, the furnace keeps the temperature inside the building at 23degreesc. at noon the furnace is turned off, and the people go home. the temperature outside is a constant 16degreesc for the rest of the afternoon. if the time constant for the building is 3 hr, when will the temperature inside the building reach 18degreesc? if some windows are left open and the time constant drops to 2 hr, when will the temperature inside reach 18degreesc?