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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 575 · 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 = [35, 96, 38, 38, 74];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  2. 2.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 3 (b) 0, 1, 2 (c) 0, 1, 2, 3 (d) 1, 2, 3
  3. 3.🔁 What number does this code show?
    let runs = [13, 13, 14, 10];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  4. 4.🔁 What number does this code show?
    let marks = [5, 4, 5];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  5. 5.🔁 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
  6. 6.🔁 What number does this code show?
    let runs = [4, 15, 15];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  7. 7.🔁 What number does this code show?
    let marks = [7, 14, 9];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  8. 8.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Aman", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Meera (c) Hi, Zoya (d) Hi, Aman
  9. 9.🔁 What number does this code show?
    let marks = [18, 13, 14, 18];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  10. 10.🔁 list.length tells you ___. (a) the biggest item (b) the last item (c) the first item (d) how many items it has
  11. 11.🔁 What number does this code show?
    let marks = [61, 88, 27, 28, 60];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  12. 12.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Meera", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Meera (c) Hi, Zoya (d) Hi, Kabir
  13. 13.🔁 What number does this code show?
    let steps = [3, 4, 13];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  14. 14.🔁 What number does this code show?
    let marks = [15, 5, 9];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  15. 15.🔁 What number does this code show?
    let steps = [12, 18, 4, 14];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  16. 16.🔁 What number does this code show?
    let marks = [5, 18, 4, 18, 15];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  17. 17.🔁 What number does this code show?
    let runs = [13, 8, 13, 11];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  18. 18.🔁 What number does this code show?
    let steps = [47, 44, 95, 45, 96];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  19. 19.🔁 What number does this code show?
    let marks = [20, 52, 41, 89];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  20. 20.🔁 What number does this code show?
    let runs = [4, 11, 3, 6];
    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 marks = [8, 20, 4, 10];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  22. 22.🔁 A loop over a list of 5 items runs its body how many times? (a) 6 (b) 5 (c) 4 (d) 1
  23. 23.🔁 What number does this code show?
    let steps = [20, 2, 16, 1, 14];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  24. 24.🔁 What number does this code show?
    let steps = [10, 3, 3];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  25. 25.🔁 What number does this code show?
    let scores = [14, 1, 13, 18];
    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 runs = [7, 4, 17];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  27. 27.🔁 What number does this code show?
    let scores = [1, 14, 20];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  28. 28.🔁 What number does this code show?
    let steps = [36, 12, 40, 95];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  29. 29.🔁 What number does this code show?
    let scores = [15, 15, 1, 9];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  30. 30.🔁 What number does this code show?
    let steps = [11, 1, 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 steps = [17, 60, 56, 96];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  32. 32.🔁 What number does this code show?
    let runs = [9, 8, 16];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  33. 33.🔁 What number does this code show?
    let scores = [96, 48, 55];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  34. 34.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Meera", "Riya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Meera (c) Hi, Arjun (d) Hi, Riya
  35. 35.🔁 What number does this code show?
    let scores = [19, 10, 5, 7];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  36. 36.🔁 What number does this code show?
    let steps = [17, 9, 5];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  37. 37.🔁 What number does this code show?
    let marks = [12, 54, 62];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  38. 38.🔁 What number does this code show?
    let steps = [5, 19, 16, 15, 18];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  39. 39.🔁 What does a loop do? (a) repeats code (b) draws icons (c) deletes code (d) saves photos
  40. 40.🔁 What number does this code show?
    let steps = [14, 19, 12, 13];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);

Answer key

  1. 2
  2. 0, 1, 2
  3. 50
  4. 14
  5. less code to write
  6. 34
  7. 30
  8. Hi, Zoya
  9. 63
  10. how many items it has
  11. 3
  12. Hi, Kabir
  13. 13
  14. 29
  15. 48
  16. 60
  17. 13
  18. 5
  19. 1
  20. 11
  21. 42
  22. 5
  23. 53
  24. 10
  25. 18
  26. 28
  27. 20
  28. 1
  29. 15
  30. 17
  31. 3
  32. 33
  33. 1
  34. Hi, Arjun
  35. 41
  36. 31
  37. 1
  38. 19
  39. repeats code
  40. 19

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