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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 339 · 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 steps = [6, 4, 7, 16, 13];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  2. 2.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Kabir", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Arjun (c) Hi, Kabir
  3. 3.🔁 What number does this code show?
    let scores = [53, 86, 34];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  4. 4.🔁 What number does this code show?
    let steps = [30, 95, 23];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  5. 5.🔁 What number does this code show?
    let runs = [1, 5, 7, 6];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  6. 6.🔁 What number does this code show?
    let marks = [24, 58, 63, 72];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  7. 7.🔁 What number does this code show?
    let steps = [42, 40, 69];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  8. 8.🔁 What does a loop do? (a) saves photos (b) repeats code (c) draws icons (d) deletes code
  9. 9.🔁 What number does this code show?
    let steps = [49, 89, 44, 14, 53];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  10. 10.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 1, 2, 3 (b) 3 (c) 0, 1, 2, 3 (d) 0, 1, 2
  11. 11.🔁 Why use a loop to show 100 messages? (a) it is slower (b) it uses more lines (c) it hides them (d) less code to write
  12. 12.🔁 What number does this code show?
    let steps = [37, 40, 27, 12];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  13. 13.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Zoya", "Meera", "Riya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Zoya (c) Hi, Aman (d) Hi, Meera
  14. 14.🔁 What number does this code show?
    let steps = [1, 16, 3, 15, 14];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  15. 15.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Arjun", "Riya", "Kabir", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Zoya (c) Hi, Aman (d) Hi, Arjun
  16. 16.🔁 What number does this code show?
    let runs = [10, 15, 13];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  17. 17.🔁 What number does this code show?
    let marks = [4, 5, 1];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  18. 18.🔁 What number does this code show?
    let marks = [20, 12, 18];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  19. 19.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Aman", "Kabir", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Riya (c) Hi, Kabir (d) Hi, Meera
  20. 20.🔁 What number does this code show?
    let runs = [20, 8, 20, 2, 8];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  21. 21.🔁 What number does this code show?
    let runs = [20, 2, 13, 3];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  22. 22.🔁 What number does this code show?
    let runs = [13, 14, 5, 1];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  23. 23.🔁 What number does this code show?
    let marks = [4, 6, 13, 15];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  24. 24.🔁 What number does this code show?
    let marks = [10, 6, 2];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  25. 25.🔁 What number does this code show?
    let runs = [1, 19, 8, 13, 20];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  26. 26.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Riya (c) Hi, Zoya
  27. 27.🔁 A loop over a list of 5 items runs its body how many times? (a) 1 (b) 5 (c) 4 (d) 6
  28. 28.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Zoya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Arjun (c) Hi, Zoya
  29. 29.🔁 What number does this code show?
    let steps = [7, 5, 16, 17];
    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 steps = [7, 17, 3, 6, 9];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  31. 31.🔁 What number does this code show?
    let runs = [27, 64, 14];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  32. 32.🔁 list.length tells you ___. (a) the first item (b) the last item (c) the biggest item (d) how many items it has
  33. 33.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Riya", "Aman", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Riya (c) Hi, Meera (d) Hi, Aman
  34. 34.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Arjun", "Zoya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Riya (c) Hi, Arjun (d) Hi, Meera
  35. 35.🔁 What number does this code show?
    let scores = [50, 96, 80];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  36. 36.🔁 What number does this code show?
    let marks = [9, 6, 7, 1];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  37. 37.🔁 What number does this code show?
    let marks = [3, 9, 6, 9, 4];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  38. 38.🔁 What number does this code show?
    let steps = [96, 77, 36, 39, 55];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  39. 39.🔁 What number does this code show?
    let scores = [8, 2, 15, 14, 9];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  40. 40.🔁 What number does this code show?
    let marks = [3, 6, 14, 15];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);

Answer key

  1. 46
  2. Hi, Aman
  3. 2
  4. 1
  5. 7
  6. 1
  7. 0
  8. repeats code
  9. 2
  10. 0, 1, 2
  11. less code to write
  12. 1
  13. Hi, Arjun
  14. 49
  15. Hi, Zoya
  16. 15
  17. 10
  18. 50
  19. Hi, Meera
  20. 20
  21. 20
  22. 33
  23. 38
  24. 10
  25. 20
  26. Hi, Zoya
  27. 5
  28. Hi, Arjun
  29. 17
  30. 17
  31. 1
  32. how many items it has
  33. Hi, Kabir
  34. Hi, Meera
  35. 3
  36. 23
  37. 9
  38. 3
  39. 48
  40. 38

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