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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 383 · 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 = [50, 76, 36, 16];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  2. 2.🔁 What number does this code show?
    let marks = [14, 6, 12, 17];
    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 marks = [19, 68, 63, 57, 48];
    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) 6 (c) 4 (d) 5
  5. 5.🔁 What number does this code show?
    let scores = [49, 30, 83, 47, 68];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  6. 6.🔁 What number does this code show?
    let runs = [5, 6, 8, 20];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  7. 7.🔁 What number does this code show?
    let scores = [59, 63, 47, 23];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  8. 8.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Kabir", "Riya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Arjun (c) Hi, Kabir (d) Hi, Aman
  9. 9.🔁 What number does this code show?
    let marks = [46, 27, 80];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  10. 10.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Kabir", "Zoya", "Arjun", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Riya (c) Hi, Aman (d) Hi, Kabir
  11. 11.🔁 What number does this code show?
    let runs = [7, 13, 1, 4];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  12. 12.🔁 What number does this code show?
    let scores = [8, 3, 12, 3, 4];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  13. 13.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 3 (b) 0, 1, 2 (c) 1, 2, 3 (d) 0, 1, 2, 3
  14. 14.🔁 list.length tells you ___. (a) the biggest item (b) the first item (c) the last item (d) how many items it has
  15. 15.🔁 What number does this code show?
    let scores = [9, 4, 6];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  16. 16.🔁 What number does this code show?
    let steps = [70, 68, 76, 43, 17];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  17. 17.🔁 What number does this code show?
    let runs = [83, 31, 50];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  18. 18.🔁 What number does this code show?
    let steps = [25, 35, 40];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  19. 19.🔁 What number does this code show?
    let marks = [21, 98, 12];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  20. 20.🔁 What number does this code show?
    let marks = [72, 81, 82];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  21. 21.🔁 What number does this code show?
    let scores = [95, 19, 55];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  22. 22.🔁 What number does this code show?
    let steps = [3, 10, 8, 17, 18];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  23. 23.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Kabir", "Riya", "Aman", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Kabir (c) Hi, Meera (d) Hi, Arjun
  24. 24.🔁 What number does this code show?
    let scores = [1, 12, 6, 14, 13];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  25. 25.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Zoya", "Arjun", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Zoya (c) Hi, Meera (d) Hi, Kabir
  26. 26.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Arjun", "Aman", "Kabir", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Meera (c) Hi, Aman (d) Hi, Riya
  27. 27.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Kabir", "Arjun", "Meera", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Arjun (c) Hi, Zoya (d) Hi, Kabir
  28. 28.🔁 What does a loop do? (a) draws icons (b) deletes code (c) saves photos (d) repeats code
  29. 29.🔁 What number does this code show?
    let runs = [15, 3, 9];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  30. 30.🔁 What number does this code show?
    let marks = [8, 15, 7, 5, 5];
    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 = ["Kabir", "Riya", "Arjun", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Riya (c) Hi, Arjun (d) Hi, Zoya
  32. 32.🔁 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
  33. 33.🔁 What number does this code show?
    let runs = [13, 3, 3, 19];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  34. 34.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Arjun", "Aman", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Aman (c) Hi, Kabir (d) Hi, Arjun
  35. 35.🔁 What number does this code show?
    let runs = [9, 1, 6, 3, 6];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  36. 36.🔁 What number does this code show?
    let marks = [14, 6, 6, 2];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  37. 37.🔁 Why use a loop to show 100 messages? (a) it hides them (b) less code to write (c) it uses more lines (d) it is slower
  38. 38.🔁 What number does this code show?
    let scores = [5, 11, 15, 11];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  39. 39.🔁 What number does this code show?
    let runs = [9, 5, 5];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  40. 40.🔁 What number does this code show?
    let runs = [11, 16, 5];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);

Answer key

  1. 1
  2. 49
  3. 4
  4. 5
  5. 2
  6. 20
  7. 3
  8. Hi, Aman
  9. 1
  10. Hi, Riya
  11. 25
  12. 30
  13. 0, 1, 2
  14. how many items it has
  15. 19
  16. 3
  17. 2
  18. 0
  19. 1
  20. 3
  21. 1
  22. 18
  23. Hi, Arjun
  24. 14
  25. Hi, Kabir
  26. Hi, Riya
  27. Hi, Zoya
  28. repeats code
  29. 15
  30. 40
  31. Hi, Zoya
  32. Hi, Meera
  33. 19
  34. Hi, Riya
  35. 9
  36. 14
  37. less code to write
  38. 42
  39. 19
  40. 32

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