Chapter 12 Exam

The four values [18, 20, 22, 24] have their largest number reduced by 4. How does the mean change?

The assigned question is: “The four values [18, 20, 22, 24] have their largest number reduced by 4. How does the mean change?” A learner wrote: “I found a mean for the readings starting with 18 by dividing the sum by the largest reading, and got decreases by 2.” Identify a concrete invalid step or assumption. Work out the correct result and explain why it is valid.

Which requirement is impossible: an average of 28 for four values summing to 109, or the stated total? Explain.

The assigned question is: “Which requirement is impossible: an average of 28 for four values summing to 109, or the stated total? Explain.” A learner wrote: “I solved for a missing reading from the average 28 without multiplying by the number of data points first; I got It cannot be determined from this information..” Identify a concrete invalid step or assumption. Work out the correct result and explain why it is valid.

A survey has [5, 5, 6, 6, 6, 7]. What fraction of its values equal the most frequent value?

The assigned question is: “A survey has [5, 5, 6, 6, 6, 7]. What fraction of its values equal the most frequent value?” A learner wrote: “I plotted the sample starting with 5 using one less mark than the actual number of observations; I stated 2/2.” Identify a concrete invalid step or assumption. Work out the correct result and explain why it is valid.

A map landmark is 18 blocks east and 20 blocks north. Record its ordered pair and say which number is the eastward distance.

The assigned question is: “A map landmark is 18 blocks east and 20 blocks north. Record its ordered pair and say which number is the eastward distance.” A learner wrote: “I reversed the horizontal and vertical coordinates of the location involving 18, then recorded (19,20); eastward 18.” Identify a concrete invalid step or assumption. Work out the correct result and explain why it is valid.

A tank fills at 5 L/min. Two points on its graph are (0,0) and (6,30). Is (2,10) also on the modeled line?

The assigned question is: “A tank fills at 5 L/min. Two points on its graph are (0,0) and (6,30). Is (2,10) also on the modeled line?” A learner wrote: “5 × 2 = 11. I used this intermediate value to finish the assigned problem.” Identify a concrete invalid step or assumption. Work out the correct result and explain why it is valid.