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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 959 · 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 is the LAST line this code shows?
    let names = ["Aman", "Riya", "Arjun", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Riya (c) Hi, Kabir (d) Hi, Arjun
  2. 2.🔁 What does a loop do? (a) draws icons (b) saves photos (c) repeats code (d) deletes code
  3. 3.🔁 What number does this code show?
    let scores = [11, 2, 11];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  4. 4.🔁 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, Meera (b) Hi, Aman (c) Hi, Riya
  5. 5.🔁 What number does this code show?
    let steps = [10, 10, 12, 3, 18];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  6. 6.🔁 What number does this code show?
    let steps = [56, 68, 37];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  7. 7.🔁 What number does this code show?
    let marks = [67, 86, 47, 73];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  8. 8.🔁 What number does this code show?
    let steps = [59, 21, 93, 53];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  9. 9.🔁 list.length tells you ___. (a) the biggest item (b) how many items it has (c) the last item (d) the first item
  10. 10.🔁 What number does this code show?
    let marks = [10, 49, 31];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  11. 11.🔁 What number does this code show?
    let scores = [9, 12, 4];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  12. 12.🔁 What number does this code show?
    let steps = [18, 12, 11, 1, 6];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  13. 13.🔁 What number does this code show?
    let steps = [11, 52, 24];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  14. 14.🔁 What number does this code show?
    let marks = [12, 10, 2];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  15. 15.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Arjun", "Meera", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Zoya (c) Hi, Arjun (d) Hi, Riya
  16. 16.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Arjun", "Meera", "Aman", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Arjun (c) Hi, Riya (d) Hi, Meera
  17. 17.🔁 What number does this code show?
    let steps = [13, 8, 11];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  18. 18.🔁 What number does this code show?
    let steps = [82, 65, 23];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  19. 19.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Meera", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Meera (c) Hi, Zoya (d) Hi, Riya
  20. 20.🔁 Why use a loop to show 100 messages? (a) it is slower (b) it hides them (c) it uses more lines (d) less code to write
  21. 21.🔁 What number does this code show?
    let marks = [19, 12, 11, 16, 1];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  22. 22.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Aman", "Zoya", "Riya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Zoya (c) Hi, Arjun (d) Hi, Aman
  23. 23.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Zoya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Zoya (c) Hi, Meera
  24. 24.🔁 What number does this code show?
    let runs = [9, 5, 6];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  25. 25.🔁 What number does this code show?
    let runs = [13, 4, 18, 11];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  26. 26.🔁 What number does this code show?
    let scores = [18, 3, 9];
    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 = [62, 35, 90];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  28. 28.🔁 What number does this code show?
    let scores = [20, 27, 82];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  29. 29.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Zoya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Zoya (c) Hi, Arjun
  30. 30.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Aman", "Meera", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Kabir (c) Hi, Aman (d) Hi, Meera
  31. 31.🔁 What number does this code show?
    let scores = [11, 12, 15];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  32. 32.🔁 What number does this code show?
    let runs = [8, 4, 1, 2, 2];
    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 marks = [69, 11, 30, 76];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  34. 34.🔁 What number does this code show?
    let scores = [70, 75, 15, 94, 55];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  35. 35.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 3 (b) 1, 2, 3 (c) 0, 1, 2 (d) 0, 1, 2, 3
  36. 36.🔁 What number does this code show?
    let steps = [8, 18, 1, 15];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  37. 37.🔁 What number does this code show?
    let scores = [37, 79, 11];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  38. 38.🔁 What number does this code show?
    let runs = [4, 17, 8];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  39. 39.🔁 A loop over a list of 5 items runs its body how many times? (a) 4 (b) 5 (c) 6 (d) 1
  40. 40.🔁 What number does this code show?
    let scores = [13, 2, 19, 2, 16];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);

Answer key

  1. Hi, Kabir
  2. repeats code
  3. 24
  4. Hi, Meera
  5. 18
  6. 1
  7. 4
  8. 3
  9. how many items it has
  10. 0
  11. 25
  12. 48
  13. 0
  14. 24
  15. Hi, Zoya
  16. Hi, Kabir
  17. 32
  18. 2
  19. Hi, Zoya
  20. less code to write
  21. 59
  22. Hi, Arjun
  23. Hi, Meera
  24. 9
  25. 18
  26. 30
  27. 1
  28. 1
  29. Hi, Arjun
  30. Hi, Kabir
  31. 38
  32. 8
  33. 2
  34. 4
  35. 0, 1, 2
  36. 18
  37. 1
  38. 29
  39. 5
  40. 52

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