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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 593 · 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.🔁 What number does this code show?
    let marks = [5, 3, 1];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  2. 2.🔁 What number does this code show?
    let marks = [12, 12, 13];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  3. 3.🔁 What number does this code show?
    let marks = [37, 67, 73];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  4. 4.🔁 A loop over a list of 5 items runs its body how many times? (a) 1 (b) 4 (c) 5 (d) 6
  5. 5.🔁 What number does this code show?
    let steps = [13, 1, 4, 15];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  6. 6.🔁 What number does this code show?
    let scores = [20, 11, 8];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  7. 7.🔁 What number does this code show?
    let scores = [9, 8, 19, 12];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  8. 8.🔁 What number does this code show?
    let steps = [13, 19, 10, 1];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  9. 9.🔁 What number does this code show?
    let steps = [13, 10, 18];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  10. 10.🔁 What number does this code show?
    let steps = [15, 1, 3, 17];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  11. 11.🔁 What number does this code show?
    let marks = [17, 9, 5];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  12. 12.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Kabir (c) Hi, Zoya
  13. 13.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Riya", "Kabir", "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 scores = [19, 10, 2];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  15. 15.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Aman", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Zoya (c) Hi, Kabir (d) Hi, Riya
  16. 16.🔁 list.length tells you ___. (a) the first item (b) how many items it has (c) the biggest item (d) the last item
  17. 17.🔁 What number does this code show?
    let scores = [3, 13, 3, 7];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  18. 18.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Meera", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Meera (c) Hi, Arjun
  19. 19.🔁 What number does this code show?
    let steps = [8, 2, 9, 4, 2];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  20. 20.🔁 What number does this code show?
    let runs = [54, 31, 17];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  21. 21.🔁 What number does this code show?
    let steps = [16, 11, 1];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  22. 22.🔁 What number does this code show?
    let runs = [47, 91, 49, 14, 34];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  23. 23.🔁 What number does this code show?
    let steps = [24, 60, 72, 39, 43];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  24. 24.🔁 What does a loop do? (a) deletes code (b) repeats code (c) draws icons (d) saves photos
  25. 25.🔁 What number does this code show?
    let marks = [55, 82, 55];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  26. 26.🔁 What number does this code show?
    let marks = [54, 15, 74, 43, 24];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  27. 27.🔁 What number does this code show?
    let scores = [11, 1, 18];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  28. 28.🔁 Why use a loop to show 100 messages? (a) it hides them (b) it uses more lines (c) less code to write (d) it is slower
  29. 29.🔁 What number does this code show?
    let steps = [27, 71, 29, 85];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  30. 30.🔁 What number does this code show?
    let scores = [20, 3, 4, 1];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  31. 31.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Zoya", "Meera", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Zoya (c) Hi, Meera (d) Hi, Aman
  32. 32.🔁 What number does this code show?
    let runs = [16, 20, 5];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  33. 33.🔁 What number does this code show?
    let runs = [82, 16, 80, 86];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  34. 34.🔁 What number does this code show?
    let scores = [2, 20, 5, 19, 3];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  35. 35.🔁 What number does this code show?
    let marks = [4, 20, 18, 17, 3];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  36. 36.🔁 What number does this code show?
    let runs = [85, 15, 11, 90, 29];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  37. 37.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 1, 2, 3 (b) 3 (c) 0, 1, 2 (d) 0, 1, 2, 3
  38. 38.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Arjun", "Riya", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Arjun (c) Hi, Kabir (d) Hi, Riya
  39. 39.🔁 What number does this code show?
    let marks = [49, 37, 17, 59, 46];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  40. 40.🔁 What number does this code show?
    let steps = [15, 5, 4];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);

Answer key

  1. 9
  2. 13
  3. 2
  4. 5
  5. 33
  6. 39
  7. 48
  8. 43
  9. 18
  10. 17
  11. 17
  12. Hi, Kabir
  13. Hi, Aman
  14. 31
  15. Hi, Kabir
  16. how many items it has
  17. 26
  18. Hi, Arjun
  19. 25
  20. 0
  21. 28
  22. 3
  23. 2
  24. repeats code
  25. 1
  26. 1
  27. 30
  28. less code to write
  29. 2
  30. 28
  31. Hi, Aman
  32. 20
  33. 3
  34. 20
  35. 20
  36. 2
  37. 0, 1, 2
  38. Hi, Kabir
  39. 0
  40. 24

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