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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 753 · 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 marks = [7, 11, 18, 17];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  2. 2.🔁 list.length tells you ___. (a) the biggest item (b) the last item (c) the first item (d) how many items it has
  3. 3.🔁 A loop over a list of 5 items runs its body how many times? (a) 6 (b) 4 (c) 1 (d) 5
  4. 4.🔁 Why use a loop to show 100 messages? (a) it is slower (b) less code to write (c) it uses more lines (d) it hides them
  5. 5.🔁 What number does this code show?
    let steps = [48, 74, 14, 20, 94];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  6. 6.🔁 What number does this code show?
    let steps = [14, 19, 1];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  7. 7.🔁 What number does this code show?
    let steps = [83, 22, 93, 12, 55];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  8. 8.🔁 What number does this code show?
    let marks = [38, 56, 59, 91];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  9. 9.🔁 What number does this code show?
    let scores = [16, 5, 9];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  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 (d) 0, 1, 2, 3
  11. 11.🔁 What number does this code show?
    let steps = [4, 11, 16, 6];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  12. 12.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Kabir", "Zoya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Zoya (c) Hi, Aman (d) Hi, Meera
  13. 13.🔁 What number does this code show?
    let marks = [5, 6, 17, 15, 12];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  14. 14.🔁 What number does this code show?
    let steps = [7, 3, 7];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  15. 15.🔁 What does a loop do? (a) deletes code (b) repeats code (c) saves photos (d) draws icons
  16. 16.🔁 What number does this code show?
    let runs = [72, 72, 67];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  17. 17.🔁 What number does this code show?
    let runs = [17, 12, 10, 18];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  18. 18.🔁 What number does this code show?
    let runs = [2, 9, 6, 15];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  19. 19.🔁 What number does this code show?
    let runs = [44, 31, 76, 37, 78];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  20. 20.🔁 What number does this code show?
    let runs = [86, 14, 25];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  21. 21.🔁 What number does this code show?
    let marks = [9, 14, 7, 14];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  22. 22.🔁 What number does this code show?
    let marks = [5, 12, 14, 1, 1];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  23. 23.🔁 What number does this code show?
    let scores = [3, 16, 19, 6];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  24. 24.🔁 What number does this code show?
    let steps = [32, 88, 81, 62, 18];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  25. 25.🔁 What number does this code show?
    let marks = [3, 12, 6, 17, 2];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  26. 26.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Zoya", "Arjun", "Riya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Zoya (c) Hi, Aman (d) Hi, Arjun
  27. 27.🔁 What number does this code show?
    let steps = [17, 11, 17, 4];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  28. 28.🔁 What number does this code show?
    let marks = [4, 20, 4, 6, 9];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  29. 29.🔁 What number does this code show?
    let steps = [20, 11, 10, 20, 9];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  30. 30.🔁 What number does this code show?
    let steps = [9, 9, 4];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  31. 31.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Aman", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Aman (c) Hi, Arjun
  32. 32.🔁 What number does this code show?
    let runs = [57, 82, 48, 76];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  33. 33.🔁 What number does this code show?
    let scores = [12, 17, 12];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  34. 34.🔁 What number does this code show?
    let scores = [16, 6, 7, 1, 12];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  35. 35.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Kabir", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Zoya (c) Hi, Meera
  36. 36.🔁 What number does this code show?
    let scores = [13, 12, 19];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  37. 37.🔁 What number does this code show?
    let steps = [87, 87, 51];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  38. 38.🔁 What number does this code show?
    let scores = [10, 17, 11, 8, 10];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  39. 39.🔁 What number does this code show?
    let steps = [11, 19, 20, 7];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  40. 40.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Aman", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Aman (c) Hi, Riya

Answer key

  1. 53
  2. how many items it has
  3. 5
  4. less code to write
  5. 2
  6. 19
  7. 3
  8. 1
  9. 30
  10. 0, 1, 2
  11. 37
  12. Hi, Aman
  13. 55
  14. 17
  15. repeats code
  16. 3
  17. 57
  18. 15
  19. 2
  20. 1
  21. 44
  22. 33
  23. 19
  24. 3
  25. 40
  26. Hi, Aman
  27. 17
  28. 20
  29. 70
  30. 22
  31. Hi, Kabir
  32. 4
  33. 41
  34. 16
  35. Hi, Meera
  36. 44
  37. 3
  38. 17
  39. 57
  40. Hi, Zoya

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