Math 165/166 Review 4 Name & Number: Show all your work to get proper credits. Otherwise, no credit will be given. This is only the review for exam and you should review other necessary work. Exam 4 covers sections 4.1,4.3,4.4,6.1-6.5. 1. Find the amount s of advertising that maximizes the profit P 0.1s 2 6s 100 , where s and P are measured in thousands of dollars and what is the maximum profit, then? 2. Fill in the table so it is exponential data and find its formula. x 0 y 2.60 2 4 210.6 631.8 3. Sketch the following functions. Label them clearly. (a) y ( x 1)2 (b) y ( x 2)2 1 (d) y log3 x (e) y ln x 1 (c) y 2 x2 4 x 1 4. (a) Divide 8x3 4 x 2 x 5 by x+3 in two methods, polynomial division, synthetic division and write your answer in two ways. (b) Use the remainder theorem to verify your remainder obtained in (a) is correct. Is (x+3) a factor of the polynomial 8x3 4 x 2 x 5 ? 5. The parents of a newborn baby infant place $10,000 in an investment that pays 8% annual interest compounded quarterly. What sum is available at the end of 18 years to finance the child’s college education? 6. Solve the equation for x. (a) log16 x 1/ 2 (b) 32 x 814/3 (d) log x log( x 3) 1 (c) log3 ( x 1) 2 (e) log 2 ( x 4) 3 log 2 ( x 2) 7. The Davis National bank pays 6% interest compounded quarterly. How long will it take for a deposit to triple in value? 8. Suppose that the number N of mopeds sold when x thousands of dollars are spent on advertising is given by N 4000 1000ln( x 2) . How much advertising money must be spent to sell 6000 mopeds? 9. If log2 s , log3 t and log5 u , then express the following in terms of s,t, and u. (a) log18 (b) log 5 (c) log1.5 (d) log 7.5 4 10. Fechner’s Logarithmic Law in psychology is used to meausred notable changes in sensory response based upon eqaul increases of a particular sensory stimulus. The law is given by the equation S k log l where S is the maginitude of the sensory experience, l is the physical intensity, and k is a scaling constant. Determine the physical intensity of a sensory experiment if the recorded magnitude of sensation is 0.5005 and the constant k 10. 11. A rectangular region with one side against an existing building is to be fenced in. If 100 feet of fencing material are available, what dimension will maximize the area of the region? What is the maximum area? Answers: 1. when x=30(thousands), profit becomes maximum $190(thousand) 2. x 0 y 2.60 2 23.4 4 210.6 5 631.8 y 2.6 3x 3. 4. (a) 8x3 4 x2 x 5 (8x2 20 x 59)( x 3) 182 or 8 x3 4 x 2 x 5 182 8 x 2 20 x 59 x3 x3 (b) if P( x) 8x3 4 x 2 x 5 , then P(3) 182 and x+3 is not a factor of P(x) because the reaminder is not eqaul to zero. 5. $41,611.40 7. 18.5 years 6. (a) 4 (b) 8/3 (c) 10 (d) 5 (e) 1 17 8. $5389 9. (a) s+2t (b) u-2s (c) t-s (d) 0.5t+0.5u-0.5s 10. 1.122147 11. 25 by 50 and maximum area is 1250 square feet

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