Statistics Summary
1. Problem 54: Find the median score of the seven students with scores 48, 62, 62, 98, 76, 88, 70.
2. Sort the scores in ascending order: 48, 62, 62, 70, 76, 88, 98.
3. Since there are 7 scores (odd number), median is the middle value, which is the 4th score.
4. The 4th score is 70.
Answer: B. 70
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5. Problem 55: Find mean, median, and mode for hourly pay rates with frequencies.
6. List pay rates with frequencies: 9.00 (4), 12.50 (29), 15.50 (7), 20.00 (4).
7. Total employees = 4 + 29 + 7 + 4 = 44.
8. Calculate mean:
$$\text{Mean} = \frac{(9*4) + (12.5*29) + (15.5*7) + (20*4)}{44} = \frac{36 + 362.5 + 108.5 + 80}{44} = \frac{587}{44} \approx 13.34$$
9. Find median:
- The median position is the $\frac{44 + 1}{2} = 22.5$th value.
- Count cumulative frequencies:
- 9.00: first 4 employees
- 12.50: next 29 employees (positions 5 to 33), so median lies in 12.50 class.
- Thus, median is 12.50.
10. Find mode: The pay rate with highest frequency is 12.50 (29 times).
Answer: Mean: 13.34, Median: 12.50, Mode: 12.50
Corresponds to C.
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11. Problem 56: Find the midrange of temperatures 54, 58, 65, 69, 71, 67, 65, 65, 60.
12. Midrange is average of minimum and maximum values.
13. Minimum = 54, Maximum = 71.
14. Midrange = $\frac{54 + 71}{2} = \frac{125}{2} = 62.5$.
Answer: D. 62.5
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15. Problem 57: Find needed fifth quiz score for mean 87 given four quiz scores: 89, 90, 82, 77.
16. Use formula: $\text{Mean} = \frac{\text{Sum of scores}}{5}.$
17. Sum of first 4 scores: $89 + 90 + 82 + 77 = 338.$
18. Let fifth score be $x.$ Then:
$$87 = \frac{338 + x}{5} \Rightarrow 338 + x = 435 \Rightarrow x = 435 - 338 = 97.$$
Answer: E. 97%
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19. Problem 58: Find weighted average grade for Maegan.
20. Weights: each test = 3 quizzes, final exam = 2 tests = 6 quizzes.
21. Maegan's scores:
- Tests: 87, 96
- Quizzes: 86, 72, 83
- Final: 93
22. Convert all to quiz-equivalent points:
- Tests: $(87 + 96) * 3 = (183)*3 = 549$ quiz-points
- Quizzes: $86 + 72 + 83 = 241$ quiz-points
- Final exam: $93 * 6 = 558$ quiz-points
23. Total quiz-points: $549 + 241 + 558 = 1348$
24. Total weight: $2*3 + 3 + 6 = 6 +3 +6 = 15$
25. Weighted mean = $\frac{1348}{15} \approx 89.87$ rounded to 90.
Answer: B. 90
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26. Problem 59: Science of collecting, organizing, analyzing, interpreting data is Statistics.
Answer: B. Statistics
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27. Problem 60: Collection of all outcomes, responses, counts of interest is Population.
Answer: E. Population
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28. Problem 61: Data entry with greatest frequency is called Mode.
Answer: E. Mode
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29. Problem 62: Mean with varying weights is Weighted Mean.
Answer: C. Weighted Mean
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30. Problem 63: Range of starting salaries 41, 38, 39, 45, 47, 41, 44, 41, 37, 42.
31. Max = 47, Min = 37
32. Range = 47 - 37 = 10.
Answer: D. 10
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33. Problem 64: If $x - 6 = 9$, find $3x + 1$.
34. Solve $x = 9 + 6 = 15$
35. Compute $3x + 1 = 3*15 +1 = 45 +1 = 46$.
Note: No matching option; re-check original problem.
Oops, options probably typo or question misread.
Answer none of above. But with given options, closest reading mistake?
If $x-6=9$ then $x=15$.
$3x+1=46$, no option matches.
Assuming typo in options or question.
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36. Problem 65: Which expression equals $b + c - d$?
Options involve expressions with products which don't simplify to the sum $b + c - d$. Answer is none matches.
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37. Problem 66: Area under standard normal curve to right of $z=1$ is approximately 0.158.
Answer: A. 0.158
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38. Problem 67: Area to right of $z=0$ is 0.5.
Answer: A. 0.50
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39. Problem 68: For mean 60, SD 10, probability of value greater than 70.
Calculate z-score:
$$z=\frac{70-60}{10} = 1$$
Area to right of $z=1$ is 0.158 or 15.8%.
Answer: A. 15.8%
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40. Problem 69: Mean 120, SD 15, probability variable > 150.
Calculate $z=\frac{150-120}{15} = 2$
Area to right of $z=2$ is approx 0.023.
Answer: A. 0.023
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41. Problem 70: Heights mean 160, SD 10, probability taller than 170.
$z=\frac{170-160}{10} = 1$
Area to right $z=1$ approx 0.158.
Answer: A. 0.158
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42. Problem 36: Longest length among 5.5cm, 5.5m, 0.0055km, 5555mm, 0.0005dm.
Convert all to cm:
- 5.5 cm = 5.5 cm
- 5.5 m = 550 cm (1 m = 100 cm)
- 0.0055 km = 550 cm (1 km = 100000 cm)
- 5555 mm = 555.5 cm (1 mm = 0.1 cm)
- 0.0005 dm = 0.005 cm (1 dm = 10 cm)
Largest is 550 cm (5.5 m or 0.0055 km).
Answer: B. 5.5 m
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43. Problem 37: Radius of circle with area $25 \pi$ cm².
Area formula: $A = \pi r^2$
Given $25 \pi = \pi r^2$, divide both sides by $\pi$:
$r^2 = 25$
$r = \sqrt{25} = 5$ cm.
Answer: D. 5 cm
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44. Problem 38: Pancake cut in 8 pieces, 3 eaten, fraction left.
Pieces left = 8 -3 = 5 pieces.
Fraction left = $\frac{5}{8}$.
Answer: C. 5/8
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45. Problem 39: First day Sept is Wednesday, find last day.
September has 30 days.
30 mod 7 = 2 remainder days.
Add 29 days to Wednesday gives same weekday.
So day 1 Wednesday, day 29 Wednesday + 28 days= Wednesday.
Day 30 = day after Wednesday (Thursday).
Answer: C. Thursday
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46. Problem 40: Angle is 25 more than supplement.
Let angle be $x$, supplement is $180 - x$.
Given $x = (180 - x) + 25$
$2x = 205$
$x = 102.5$ (larger angle).
Answer: C. 102.5
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47. Problem 41: Ruben’s grades 88,89,84,90,91,86; find Math grade for average 88.
Let Math grade be $x$.
Sum existing grades = 88 + 89 + 84 + 90 + 91 + 86 = 528.
Total grades = 7.
Mean = 88 = (528 + x)/7
Multiply:
$528 + x = 616$
$x=88$
Answer: B. 88
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48. Problem 42: Aquarium volume with length 9cm, width 5cm, height 7cm.
Volume = $l \times w \times h = 9*5*7 = 315$ cm³.
Answer: C. 315 cm³
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49. Problem 43: Median score of 8 students: 12,10,13,11,15,20,19,17.
Sort: 10,11,12,13,15,17,19,20.
Median for even n=8 is average of 4th and 5th values.
Median = $\frac{13+15}{2} = 14$.
Answer: B. 14
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50. Problem 44: Area=64, length=16, find perimeter.
Width $w = \frac{64}{16} = 4$.
Perimeter $= 2(l + w) = 2(16 +4) = 2*20 = 40$.
Answer: D. 40
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51. Problem 45: Number ways to seat 5 students at round table.
Number of arrangements for n people around a round table = $(n-1)! = 4! = 24$.
Answer: D. 24
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52. Problem 46: Midpoint joining (6,4) and (3,-4).
Midpoint $= \left(\frac{6+3}{2}, \frac{4+(-4)}{2}\right) = \left(\frac{9}{2}, 0\right)$.
Answer: D. (9/2, 0)
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53. Problem 47: Digit in thousandths place of 5672.134987 is 9.
Answer: C. 9
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54. Problem 48: 20 men build in 60 days, how many men needed for 15 days?
Using inverse proportionality:
$20 * 60 = x * 15$
$x = \frac{20 * 60}{15} = 80$ men.
Answer: C. 80
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55. Problem 49: Median score interval from frequency table.
Sum frequencies: 2+4+6+12+10+8+6+4= 52
Median position: 26.5
Cumulative frequencies:
16-23: 2
24-31: 6
32-39: 12
40-47: 24
48-55: 34
Median lies in 48-55 (since 26.5 between 24 and 34)
Answer: C. 48-55
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56. Problem 50: How much larger is $2^5$ than $5^{2n}$ (without value of n given, insufficient data).
Cannot solve.
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57. Problem 51: Mode of data 12,6,9,8,10,5,12,7 is 12 (occurs twice).
Answer: E. 12
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58. Problem 52: Same as 41 above: grade must be 88.
Answer: B. 88
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59. Problem 53: Median of math test scores same as 43 above is 14.
Answer: B. 14