Does this sample fairly show the whole group?

Answer Key - Grade 7 Math Worksheet

Circle the best answer, or write your answer on the line.

1. 1.

   Ari measured all 10 kites, then picked the 4 kites that flew longest. A gust showed off. How far is the mean of the 4 picked from the mean of all 10?

   5.5
2. 2.

   Luz measured all 10 bus rides, then picked the 4 shortest rides. The bus did not stop for ducks. How far is the mean of the 4 picked from the mean of all 10?

   5
3. 3.

   Tala measured all 10 riders, then picked 4 cards from a shuffled set of 10. One helmet had stickers. How far is the mean of the 4 picked from the mean of all 10?

   1
4. 4.

   Picture each of the 180 students as one dot on a dot plot. A sample is the few dots picked. Bo wants to know how many minutes the 180 students at Oak Middle School spend on homework. Which plan gives the sample most likely to fairly show all 180?

   • Number every student and pick 12 numbers at random.
   • Ask the 12 students in the math club.
   • Number every student and pick 2 numbers at random, and use just those
   • Ask the 12 students who answer an online poll.
5. 5.

   Picture each of the 140 players as one dot on a dot plot. A sample is the few dots picked. Zee wants to know how many minutes the 140 players in a soccer league practice each week. Which plan gives the sample most likely to fairly show all 140?

   • Shuffle 140 player cards and deal out 2, then stop there
   • Ask the 14 players on the top team.
   • Shuffle 140 player cards and deal out 14.
   • Ask the 14 players at today's practice.
6. 6.

   Kira measured heights in centimeters for 10 bean plants. Kira picked the 4 plants nearest the sunny window. Which statement about the sample is true?

   • It is biased, because the picked dots all come from one part of the plot.
   • It is fair, because every dot had the same chance of being picked.
   • It is fair, because Kira recorded each picked bean plant carefully.
   • It is biased, because it has fewer dots than the whole group.
7. 7.

   Ren measured minutes of practice a day for 10 numbered piano students. Ren drew 4 numbers from a bag of 10. Which statement about the sample is true?

   • It is biased, because it has fewer dots than the whole group.
   • It is biased, because the picked dots all come from one part of the plot.
   • It is fair, because Ren recorded each picked piano student carefully.
   • It is fair, because every dot had the same chance of being picked.
8. 8.

   Esme measured minutes of reading a night for 10 numbered club members. Esme dealt 4 cards from 10 shuffled name cards. Which statement about the sample is true?

   • It is biased, because it has fewer dots than the whole group.
   • It is fair, because Esme recorded each picked club member carefully.
   • It is fair, because every dot had the same chance of being picked.
   • It is biased, because the picked dots all come from one part of the plot.
9. 9.

   Noah measured inches in a standing long jump for 10 jumpers. Noah picked the 4 jumpers on the school team. Which statement about the sample is true?

   • It is biased, because the picked dots all come from one part of the plot.
   • It is fair, because every dot had the same chance of being picked.
   • It is biased, because it has fewer dots than the whole group.
   • It is fair, because Noah recorded each picked jumper carefully.
10. 10.

    Ari measured lengths in centimeters for 10 numbered shells. Ari drew 4 numbers from a bag of 10. Which statement about the sample is true?

    • It is fair, because Ari recorded each picked shell carefully.
    • It is biased, because the picked dots all come from one part of the plot.
    • It is biased, because it has fewer dots than the whole group.
    • It is fair, because every dot had the same chance of being picked.