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.

   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
3. 3.

   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
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?

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

   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 10 book cards from a box holding all 250 cards.
   • Check the 10 books students recommend.
   • Draw 2 book cards from a box holding all 250 cards, then stop
   • Check the 10 books on the lowest shelf.
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 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 Kira recorded each picked bean plant carefully.
   • It is fair, because every dot had the same chance of being picked.
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 the picked dots all come from one part of the plot.
   • It is fair, because Ren recorded each picked piano student carefully.
   • 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.
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 the picked dots all come from one part of the plot.
   • It is fair, because Esme recorded each picked club member carefully.
   • 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.
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 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 Noah recorded each picked jumper carefully.
   • It is biased, because it has fewer dots than the whole group.
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 fair, because Ari recorded each picked shell carefully.
    • 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.