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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 158 · 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 = [9, 3, 10, 6];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  2. 2.🔁 What number does this code show?
    let marks = [15, 8, 10];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  3. 3.🔁 What number does this code show?
    let scores = [9, 15, 20, 6];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  4. 4.🔁 What number does this code show?
    let runs = [37, 82, 73, 31];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  5. 5.🔁 What number does this code show?
    let scores = [65, 73, 14, 86, 34];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  6. 6.🔁 What does a loop do? (a) saves photos (b) deletes code (c) draws icons (d) repeats code
  7. 7.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Arjun", "Riya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Riya (c) Hi, Aman (d) Hi, Kabir
  8. 8.🔁 What number does this code show?
    let steps = [18, 5, 14, 11];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  9. 9.🔁 Why use a loop to show 100 messages? (a) it uses more lines (b) it hides them (c) it is slower (d) less code to write
  10. 10.🔁 What number does this code show?
    let runs = [65, 44, 13, 49];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  11. 11.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Riya (c) Hi, Meera
  12. 12.🔁 What number does this code show?
    let scores = [5, 13, 12, 16];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  13. 13.🔁 What number does this code show?
    let runs = [18, 10, 2];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  14. 14.🔁 What number does this code show?
    let scores = [3, 18, 12];
    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 = ["Meera", "Riya", "Kabir", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Riya (c) Hi, Kabir (d) Hi, Meera
  16. 16.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 1, 2, 3 (b) 0, 1, 2, 3 (c) 0, 1, 2 (d) 3
  17. 17.🔁 What number does this code show?
    let marks = [20, 4, 10, 9, 4];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  18. 18.🔁 A loop over a list of 5 items runs its body how many times? (a) 1 (b) 4 (c) 5 (d) 6
  19. 19.🔁 What number does this code show?
    let scores = [11, 2, 2];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  20. 20.🔁 What number does this code show?
    let scores = [69, 92, 88, 94, 43];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  21. 21.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Kabir", "Zoya", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Zoya (c) Hi, Meera (d) Hi, Kabir
  22. 22.🔁 What number does this code show?
    let marks = [2, 18, 20, 19];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  23. 23.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Aman", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Meera (c) Hi, Aman
  24. 24.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Arjun", "Kabir", "Riya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Aman (c) Hi, Kabir (d) Hi, Arjun
  25. 25.🔁 What number does this code show?
    let scores = [20, 6, 16];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  26. 26.🔁 What number does this code show?
    let scores = [12, 4, 20];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  27. 27.🔁 What number does this code show?
    let runs = [6, 8, 6, 14];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  28. 28.🔁 What number does this code show?
    let scores = [16, 13, 5, 2, 6];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  29. 29.🔁 What number does this code show?
    let steps = [18, 14, 9, 11, 17];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  30. 30.🔁 What number does this code show?
    let steps = [12, 3, 5];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  31. 31.🔁 What number does this code show?
    let runs = [86, 17, 54];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  32. 32.🔁 What number does this code show?
    let steps = [4, 4, 1, 16, 18];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  33. 33.🔁 What number does this code show?
    let scores = [14, 13, 20, 6];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  34. 34.🔁 What number does this code show?
    let marks = [91, 76, 91, 79, 23];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  35. 35.🔁 What number does this code show?
    let marks = [68, 19, 70, 84];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  36. 36.🔁 What number does this code show?
    let scores = [76, 23, 54, 33, 12];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  37. 37.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Zoya", "Arjun", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Riya (c) Hi, Meera (d) Hi, Zoya
  38. 38.🔁 What number does this code show?
    let steps = [13, 17, 4, 7, 4];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  39. 39.🔁 list.length tells you ___. (a) the biggest item (b) how many items it has (c) the first item (d) the last item
  40. 40.🔁 What number does this code show?
    let marks = [17, 12, 3, 9];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);

Answer key

  1. 10
  2. 33
  3. 20
  4. 2
  5. 3
  6. repeats code
  7. Hi, Aman
  8. 48
  9. less code to write
  10. 1
  11. Hi, Meera
  12. 46
  13. 18
  14. 33
  15. Hi, Arjun
  16. 0, 1, 2
  17. 47
  18. 5
  19. 15
  20. 4
  21. Hi, Meera
  22. 59
  23. Hi, Meera
  24. Hi, Aman
  25. 20
  26. 20
  27. 14
  28. 42
  29. 69
  30. 20
  31. 2
  32. 18
  33. 20
  34. 4
  35. 3
  36. 1
  37. Hi, Meera
  38. 17
  39. how many items it has
  40. 17

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