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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 233 · 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.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 3 (b) 0, 1, 2, 3 (c) 0, 1, 2 (d) 1, 2, 3
  2. 2.🔁 What number does this code show?
    let scores = [20, 19, 17, 12, 3];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  3. 3.🔁 What number does this code show?
    let scores = [12, 5, 12, 1];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  4. 4.🔁 What does a loop do? (a) repeats code (b) saves photos (c) draws icons (d) deletes code
  5. 5.🔁 list.length tells you ___. (a) how many items it has (b) the last item (c) the first item (d) the biggest item
  6. 6.🔁 What number does this code show?
    let scores = [12, 17, 40, 13, 74];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  7. 7.🔁 What number does this code show?
    let scores = [10, 11, 17, 19];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  8. 8.🔁 What number does this code show?
    let marks = [56, 43, 66, 15];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  9. 9.🔁 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
  10. 10.🔁 What number does this code show?
    let steps = [18, 7, 7];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  11. 11.🔁 What number does this code show?
    let steps = [14, 3, 16, 6, 4];
    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 = ["Riya", "Arjun", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Riya (c) Hi, Meera
  13. 13.🔁 What number does this code show?
    let scores = [18, 6, 11];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  14. 14.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Aman", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Zoya (c) Hi, Arjun
  15. 15.🔁 What number does this code show?
    let runs = [92, 70, 87];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  16. 16.🔁 What number does this code show?
    let marks = [10, 19, 9];
    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 marks = [20, 16, 18, 4];
    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 runs = [25, 54, 36, 59, 15];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  19. 19.🔁 What number does this code show?
    let scores = [11, 19, 8, 6, 2];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  20. 20.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Kabir", "Riya", "Zoya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Riya (c) Hi, Meera (d) Hi, Kabir
  21. 21.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Aman", "Riya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Aman (c) Hi, Riya (d) Hi, Arjun
  22. 22.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Zoya", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Zoya (c) Hi, Riya
  23. 23.🔁 What number does this code show?
    let runs = [21, 36, 68];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  24. 24.🔁 What number does this code show?
    let runs = [6, 2, 19, 18, 8];
    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 steps = [10, 10, 12];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  26. 26.🔁 What number does this code show?
    let steps = [14, 12, 20];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  27. 27.🔁 What number does this code show?
    let runs = [11, 8, 1];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  28. 28.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Riya", "Kabir", "Meera", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Aman (c) Hi, Kabir (d) Hi, Arjun
  29. 29.🔁 What number does this code show?
    let runs = [6, 6, 5];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  30. 30.🔁 What number does this code show?
    let scores = [33, 14, 31, 29, 88];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  31. 31.🔁 A loop over a list of 5 items runs its body how many times? (a) 5 (b) 6 (c) 1 (d) 4
  32. 32.🔁 What number does this code show?
    let scores = [10, 15, 11, 2, 5];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  33. 33.🔁 What number does this code show?
    let marks = [11, 16, 20, 5];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  34. 34.🔁 What number does this code show?
    let marks = [60, 53, 19];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  35. 35.🔁 What number does this code show?
    let runs = [9, 16, 7, 7, 17];
    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 steps = [47, 92, 99];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  37. 37.🔁 What number does this code show?
    let steps = [7, 12, 9];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  38. 38.🔁 What number does this code show?
    let marks = [1, 8, 12, 17, 7];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  39. 39.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Riya (c) Hi, Aman
  40. 40.🔁 What number does this code show?
    let steps = [74, 98, 57];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);

Answer key

  1. 0, 1, 2
  2. 71
  3. 12
  4. repeats code
  5. how many items it has
  6. 1
  7. 57
  8. 3
  9. less code to write
  10. 32
  11. 43
  12. Hi, Meera
  13. 35
  14. Hi, Arjun
  15. 3
  16. 38
  17. 58
  18. 2
  19. 19
  20. Hi, Aman
  21. Hi, Arjun
  22. Hi, Riya
  23. 1
  24. 19
  25. 12
  26. 46
  27. 20
  28. Hi, Aman
  29. 17
  30. 1
  31. 5
  32. 43
  33. 20
  34. 1
  35. 17
  36. 3
  37. 28
  38. 17
  39. Hi, Aman
  40. 2

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