Solve the below:
Q1). An open rectangular box with square ends is to hold 6400 cm^3. It is built at a cost of $ 75/ cm^2 for the base and $25/ cm ^2 for the sides. Find the most economical dimensions.
Q2). A wall 8 meter high is 3 3/8 meter from a house. Find the shortest ladder which will reach from the ground to the house when leaning over the wall.
Q3). A company has the following schedule of charges : $30 per 1000 for orders of 50 000 or fewer , with the charge per thousand decreased by $ 0.375 for each thousand above 50 000. Find the order that will make the receipts a maximum.
Q4). Find the minimum distance from the point ( 3 , 4 ) to the parabola Y^2 = 8x