C Challenge

32. 1. It costs $20 to interview each person for a survey. Find the cost to obtain a ± 3 % plus minus 3 percent  margin of error.
    2. Reasoning Find the cost to obtain a ± 2 % plus minus 2 percent  margin of error. Why do you think polls with smaller margins of error are rare?
33. Elections A poll of 150 voters shows that a candidate is preferred by 56% of the voters while 44% prefer the opponent. Should the candidate be concerned? Explain your reasoning.

Standardized Test Prep

SAT/ACT

34. To determine the most popular brands of tea consumed by Americans, a survey is conducted in a busy downtown location at lunchtime. Which of the following is NOT a potential bias in the sampling method?
    1. Urban office employees are not representative of the general population.
    2. The results could be influenced by national brand teas available in the area.
    3. A lunchtime survey does not reflect peoples’ tastes at other times of the day.
    4. The survey must include call-in and online responses.

35. Which is the equation for the graph of the circle below?

    

    6. x 2 + ( y − 5 ) 2 = 16 x squared , plus . open y minus 5 close squared . equals 16
    7. x 2 + ( y + 5 ) 2 = 16 x squared , plus . open y plus 5 close squared . equals 16
    8. ( x − 5 ) 2 + y 2 = 16 open x minus 5 close squared . plus , y squared , equals 16
    9. ( x + 5 ) 2 + y 2 = 16 open x plus 5 close squared . plus , y squared , equals 16
36. A bag contains 5 red marbles, 1 blue marble, 3 yellow marbles, and 2 green marbles. One marble is drawn from the bag, the color is noted, and then the marble is replaced. The experiment is repeated. What is the probability that the first marble drawn is red and the second marble drawn is not red?
    1. 1
    2. 1 2 1 half
    3. 30 121 30 over 121
    4. 1 11 1 eleventh

Short Response

37. What is the sum of the infinite geometric sequence? Show your work.

    2 5 , 4 25 , 8 125 , ⋯ 2 fifths , comma , 4 twenty fifths , comma , 8 over 125 , comma math axis ellipsis

Mixed Review

See Lesson 11-6.

Find the mean and the standard deviation for each data set.

38. 0, 1, 1, 1, 2, 2, 2, 3, 3, 4, 5, 10
39. 1, 1, 2, 2, 3, 4, 5, 6, 8, 9, 10, 10, 12

See Lesson 6-7.

Find the inverse of each function. Is the inverse a function?

40. f ( x ) = 2 x + 5 f open x close equals 2 x plus 5
41. f ( x ) = x 2 f open x close equals , x squared
42. f ( x ) = 5 x 2 9 f open x close equals . fraction 5 , x squared , over 9 end fraction
43. f ( x ) = 3 x f open x close equals 3 square root of x

Get Ready! To prepare for Lesson 11-8, do Exercises 44–47.

See Lesson 11-1.

Evaluate each expression.

44.   4 C 2 sub 4 , cap c sub 2
45.   3 C 3 sub 3 , cap c sub 3
46.   5 C 2 sub 5 , cap c sub 2
47.   12 C 7 sub 12 , cap c sub 7

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