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.

   Jun measured all 10 tomato plants, then picked 4 tags from a bag of 10. The scarecrow had no opinion. How far is the mean of the 4 picked from the mean of all 10?

   0.5
5. 5.

   Picture each of the 300 students as one dot on a dot plot. A sample is the few dots picked. Pia wants to know how many hours the 300 students at Pine School sleep on school nights. Which plan gives the sample most likely to fairly show all 300?

   • Draw 15 names from a hat holding all 300 names.
   • Ask the 15 students who ride the early bus.
   • Draw 3 names from a hat holding all 300 names.
   • Ask the 15 students waiting in the front office.
6. 6.

   Picture each of the 250 books as one dot on a dot plot. A sample is the few dots picked. Milo wants to know how many pages the 250 books on the class shelves have. Which plan gives the sample most likely to fairly show all 250?

   • Draw 2 book cards from a box holding all 250 cards, then stop
   • Draw 10 book cards from a box holding all 250 cards.
   • Check the 10 books students recommend.
   • Check the 10 books on the lowest shelf.
7. 7.

   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?

   • Ask the 14 players at today's practice.
   • Shuffle 140 player cards and deal out 2, then stop there
   • Shuffle 140 player cards and deal out 14.
   • Ask the 14 players on the top team.
8. 8.

   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 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 Kira recorded each picked bean plant carefully.
   • It is biased, because the picked dots all come from one part of the plot.
9. 9.

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