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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 82 · 40 questions
TalentJR

Developer's tip (One by one): for (let i = 0; i < list.length; i++) visits every item, from position 0. Total: add each item. Count: add 1 when the test is true. Best: keep the biggest so far. The body runs once per item: a list of 5 runs it 5 times.

NameDateTime takenScore ___ / 40
  1. 1.🔁 list.length tells you ___. (a) the biggest item (b) the last item (c) the first item (d) how many items it has
  2. 2.🔁 What number does this code show?
    let steps = [26, 16, 79];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  3. 3.🔁 What number does this code show?
    let steps = [5, 1, 12];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  4. 4.🔁 What number does this code show?
    let marks = [2, 19, 5, 7, 19];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  5. 5.🔁 What does a loop do? (a) draws icons (b) repeats code (c) saves photos (d) deletes code
  6. 6.🔁 What number does this code show?
    let marks = [3, 2, 1, 8];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  7. 7.🔁 What number does this code show?
    let steps = [14, 19, 15, 7, 13];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  8. 8.🔁 A loop over a list of 5 items runs its body how many times? (a) 1 (b) 6 (c) 4 (d) 5
  9. 9.🔁 What number does this code show?
    let marks = [11, 15, 12];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  10. 10.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Arjun", "Kabir", "Meera", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Riya (c) Hi, Arjun (d) Hi, Zoya
  11. 11.🔁 What number does this code show?
    let scores = [15, 15, 17, 12, 17];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  12. 12.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Zoya", "Riya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Kabir (c) Hi, Zoya (d) Hi, Arjun
  13. 13.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Arjun", "Riya", "Zoya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Riya (c) Hi, Arjun (d) Hi, Aman
  14. 14.🔁 What number does this code show?
    let runs = [4, 13, 8, 5, 2];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  15. 15.🔁 What number does this code show?
    let marks = [87, 27, 30];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  16. 16.🔁 What number does this code show?
    let scores = [5, 20, 9, 8, 14];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  17. 17.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Zoya", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Riya (c) Hi, Arjun
  18. 18.🔁 What number does this code show?
    let marks = [6, 19, 18];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  19. 19.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Zoya", "Kabir", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Zoya (c) Hi, Kabir (d) Hi, Arjun
  20. 20.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Arjun", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Riya (c) Hi, Zoya (d) Hi, Arjun
  21. 21.🔁 What number does this code show?
    let steps = [17, 7, 9, 4];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  22. 22.🔁 Why use a loop to show 100 messages? (a) less code to write (b) it is slower (c) it hides them (d) it uses more lines
  23. 23.🔁 What number does this code show?
    let scores = [10, 5, 16, 2, 14];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  24. 24.🔁 What number does this code show?
    let marks = [83, 35, 27, 45];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  25. 25.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Aman", "Zoya", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Kabir (c) Hi, Riya (d) Hi, Aman
  26. 26.🔁 What number does this code show?
    let scores = [2, 11, 8, 5, 16];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  27. 27.🔁 What number does this code show?
    let scores = [59, 25, 10];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  28. 28.🔁 What number does this code show?
    let scores = [10, 14, 6];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  29. 29.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 0, 1, 2 (b) 3 (c) 1, 2, 3 (d) 0, 1, 2, 3
  30. 30.🔁 What number does this code show?
    let scores = [20, 95, 28];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  31. 31.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Aman", "Riya", "Meera", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Zoya (c) Hi, Riya (d) Hi, Arjun
  32. 32.🔁 What number does this code show?
    let runs = [11, 67, 74, 65, 24];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  33. 33.🔁 What number does this code show?
    let runs = [8, 3, 8];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  34. 34.🔁 What number does this code show?
    let runs = [4, 20, 2, 3];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  35. 35.🔁 What number does this code show?
    let runs = [6, 6, 6, 10];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  36. 36.🔁 What number does this code show?
    let runs = [8, 17, 12, 3, 11];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  37. 37.🔁 What number does this code show?
    let runs = [87, 63, 94, 46];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  38. 38.🔁 What number does this code show?
    let steps = [10, 14, 8];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  39. 39.🔁 What number does this code show?
    let marks = [87, 54, 94, 25];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  40. 40.🔁 What number does this code show?
    let runs = [12, 7, 1];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);

Answer key

  1. how many items it has
  2. 1
  3. 18
  4. 19
  5. repeats code
  6. 14
  7. 19
  8. 5
  9. 15
  10. Hi, Zoya
  11. 76
  12. Hi, Kabir
  13. Hi, Aman
  14. 32
  15. 1
  16. 56
  17. Hi, Riya
  18. 19
  19. Hi, Arjun
  20. Hi, Meera
  21. 37
  22. less code to write
  23. 47
  24. 1
  25. Hi, Riya
  26. 42
  27. 0
  28. 14
  29. 0, 1, 2
  30. 1
  31. Hi, Zoya
  32. 3
  33. 19
  34. 29
  35. 28
  36. 51
  37. 3
  38. 14
  39. 3
  40. 20

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