WORD+PROBLEMS+CHAPTER+6

Many word problems encountered during Chapter 6 do not use new methods, but simply involve using substituion with equations. Examples:

The relationship between the flow of electricty, I, in a circuit, the resistance to the flow, Z, called impedance, and the electromotive force, E, called voltage, is given by the formula E= IxE. Electrical engineers use i to represent the imaginary unit. An electrical engineer is designing a circuit that is to have a current of (6-8i) amps. If impedance of the circuit is (14+8i) ohms, find the voltage.

E= IxZ E=(14+8i)(6-8i) E=84-112i+48+64 E=148-64i

Two and one-half years ago, Connor deposited the 1500 dollars he earned at a summer job in his account. His account earns 7.5% interest annually. Now, he is withdrawing the money and the interest to buy a car. Use the formula A=P(1 + r)^t, where A is the amount of money in the account after t years if the interest rate is r and the begining is P, to find how much money Connor has to buy the car.

A=P(1 + r)^t A=1500(1+.075)^5/2 A=1500(.075^5/2) A=1797.50 Dollars

A technician is tuning a piano. The frequency of the A note above middle C is correctly set at 440 vibrations per seconds. The frequency f of a note n notes above A should be f=440(12th root of 2)^n-1.

A. At what frequency shoud the tecnician set the A this 12 notes above the A above the middle C? f= 440(12th root of 2)12-1 f= 830.61 hz B. Middle C is nine notes below A that has frequency 440 vibrations per second. What should the frequency of middle C be? f= 440(12th root of 2)-9-1 f= 261.63 hz