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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 951 · 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 scores = [5, 3, 20];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  2. 2.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Arjun", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Aman (c) Hi, Arjun
  3. 3.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Aman (c) Hi, Zoya
  4. 4.🔁 What number does this code show?
    let scores = [8, 8, 11, 10, 1];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  5. 5.🔁 What number does this code show?
    let steps = [40, 74, 77, 51];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  6. 6.🔁 What number does this code show?
    let runs = [42, 35, 66, 37, 53];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  7. 7.🔁 What number does this code show?
    let scores = [6, 2, 6, 9];
    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 runs = [20, 13, 10];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  9. 9.🔁 What number does this code show?
    let scores = [5, 16, 5, 10, 12];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  10. 10.🔁 What number does this code show?
    let steps = [12, 14, 1, 7, 14];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  11. 11.🔁 A loop over a list of 5 items runs its body how many times? (a) 5 (b) 6 (c) 1 (d) 4
  12. 12.🔁 What does a loop do? (a) deletes code (b) repeats code (c) saves photos (d) draws icons
  13. 13.🔁 What number does this code show?
    let steps = [30, 12, 20, 48, 80];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  14. 14.🔁 What number does this code show?
    let scores = [15, 77, 34, 94, 21];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  15. 15.🔁 What number does this code show?
    let runs = [94, 68, 31];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  16. 16.🔁 What number does this code show?
    let steps = [1, 17, 17];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  17. 17.🔁 What number does this code show?
    let scores = [3, 7, 11];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  18. 18.🔁 What number does this code show?
    let runs = [7, 4, 10, 16, 17];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  19. 19.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Zoya", "Kabir", "Arjun", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Meera (c) Hi, Kabir (d) Hi, Zoya
  20. 20.🔁 What number does this code show?
    let steps = [86, 46, 63, 52, 59];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  21. 21.🔁 What number does this code show?
    let steps = [19, 3, 1, 11, 15];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  22. 22.🔁 What number does this code show?
    let scores = [3, 16, 1];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  23. 23.🔁 What number does this code show?
    let steps = [3, 12, 15];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  24. 24.🔁 list.length tells you ___. (a) the biggest item (b) the first item (c) how many items it has (d) the last item
  25. 25.🔁 What number does this code show?
    let runs = [15, 7, 10];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  26. 26.🔁 What number does this code show?
    let scores = [90, 56, 66];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  27. 27.🔁 What number does this code show?
    let runs = [2, 11, 1];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  28. 28.🔁 Why use a loop to show 100 messages? (a) it hides them (b) it is slower (c) less code to write (d) it uses more lines
  29. 29.🔁 What number does this code show?
    let steps = [17, 14, 5, 6];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  30. 30.🔁 What number does this code show?
    let marks = [3, 5, 13, 3];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  31. 31.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Riya (c) Hi, Zoya
  32. 32.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Aman", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Zoya (c) Hi, Riya (d) Hi, Aman
  33. 33.🔁 What number does this code show?
    let runs = [42, 95, 62, 46];
    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 steps = [34, 28, 78, 11];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  35. 35.🔁 What number does this code show?
    let scores = [4, 3, 14];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  36. 36.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Aman", "Meera", "Kabir", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Aman (c) Hi, Riya (d) Hi, Zoya
  37. 37.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Arjun", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Kabir (c) Hi, Riya (d) Hi, Zoya
  38. 38.🔁 What number does this code show?
    let runs = [18, 20, 11];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  39. 39.🔁 What number does this code show?
    let runs = [88, 35, 79, 58, 29];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  40. 40.🔁 What number does this code show?
    let steps = [1, 19, 5, 7, 11];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);

Answer key

  1. 20
  2. Hi, Zoya
  3. Hi, Zoya
  4. 38
  5. 4
  6. 0
  7. 23
  8. 20
  9. 16
  10. 48
  11. 5
  12. repeats code
  13. 1
  14. 2
  15. 2
  16. 35
  17. 11
  18. 54
  19. Hi, Meera
  20. 4
  21. 19
  22. 16
  23. 30
  24. how many items it has
  25. 32
  26. 3
  27. 14
  28. less code to write
  29. 17
  30. 24
  31. Hi, Meera
  32. Hi, Arjun
  33. 1
  34. 1
  35. 14
  36. Hi, Zoya
  37. Hi, Zoya
  38. 20
  39. 2
  40. 43

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