Asheet of paper 90 cm-by-66 cm is made into an open box (i. e. there's no top), by cutting x-cm squares out of each corner and folding up the sides. find the value of x that maximizes the volume of the box. give your answer in the simplified radical form. x = is the max.

Ahe-xe mixture containing a 0.75 mole fraction of helium is used for cooling electronics in an avionics application. at a temperature of 300 k and atmospheric pressure, calculate the mass fraction of helium and the mass density, molar concentration and molecular weight of the mixture. if the cooling capacity is 10 l, what is the mass of the coolant?