Basic Engineering Mathematics, Fifth Edition

Solving simple equations 81

7. An alloy contains 60% by weight of copper,
   the remainder being zinc. How much copper
   must be mixed with 50kg of this alloy to give
   an alloy containing 75% copper?


8. A rectangular laboratory has a length equal to
   one and a half times its width and a perimeter
   of 40m. Find its length and width.
   9. Applying the principle of moments to a beam
   results in the following equation:

F× 3 =( 5 −F)× 7

whereFis the force in newtons. Determine

the value ofF.