C2 Quiz

• When scores are grouped, it is desirable to use 10-20 class intervals.
• The lowest score is 23 and the highest score is 87. The preferred class interval width would be 5.
• We plan to use an interval size of four, and 14 is the lowest score in our sample. According to our guidelines, 12-15 would be the best choice for the bottom interval.
• John uses our guidelines to arrive at an interval size of 30. The most likely value for the range of scores in his sample is 385.
• If measurement is to the nearest 10 pounds, then a score of 540 pounds means 535.0-545.0 pounds.
• If 32 points are earned on an achievement test, this score is best considered as representing an ability of 32, exactly.
• In general, we prefer to round numbers up when they fall between two possible values.
• Rounding up gives us more information about the data than does rounding down.
• A score of 96% on a quiz can be rounded up or down to the nearest whole number (either 96 or 97).
• The exact limits of the interval 50-54 are 49.5-54.5.
• Twelve cases fall in the interval 40-49, and the relative frequency for that interval is .20. The total number of cases for the entire distribution is 60.
• he exact limits of the interval 50-54 are  49.5-54.5.
• Plotting the graph of a cumulative distribution differs from plotting the graph of an uncummulated distribution in that cumulative frequency is plotted at the upper exact limit of the interval.
• Three square inches out of the total area under a frequency curve of 12 square inches falls below a score of 68. If the curve is based on a total of 80 cases, how many cases fall below a score of 68? 20.