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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 421 · 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 = [28, 18, 34, 55];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  2. 2.🔁 What number does this code show?
    let scores = [17, 20, 9, 12, 15];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  3. 3.🔁 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
  4. 4.🔁 What number does this code show?
    let steps = [20, 5, 14, 1];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  5. 5.🔁 What number does this code show?
    let marks = [14, 8, 13, 3, 7];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  6. 6.🔁 What number does this code show?
    let steps = [10, 68, 61];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  7. 7.🔁 What number does this code show?
    let steps = [3, 13, 9];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  8. 8.🔁 list.length tells you ___. (a) the last item (b) the first item (c) the biggest item (d) how many items it has
  9. 9.🔁 What number does this code show?
    let marks = [4, 10, 3, 6, 10];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  10. 10.🔁 What number does this code show?
    let marks = [81, 29, 86, 71];
    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 marks = [18, 16, 12, 18, 6];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  12. 12.🔁 A loop over a list of 5 items runs its body how many times? (a) 1 (b) 4 (c) 5 (d) 6
  13. 13.🔁 What number does this code show?
    let runs = [27, 57, 71, 71];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  14. 14.🔁 What number does this code show?
    let steps = [76, 84, 84];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  15. 15.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Zoya", "Meera", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Meera (c) Hi, Aman (d) Hi, Zoya
  16. 16.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Arjun", "Meera", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Zoya (c) Hi, Kabir (d) Hi, Meera
  17. 17.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Aman", "Riya", "Kabir", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Aman (c) Hi, Zoya (d) Hi, Arjun
  18. 18.🔁 What number does this code show?
    let marks = [69, 67, 45];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  19. 19.🔁 What number does this code show?
    let steps = [5, 5, 4];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  20. 20.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Aman", "Riya", "Arjun", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Meera (c) Hi, Kabir (d) Hi, Riya
  21. 21.🔁 What number does this code show?
    let scores = [11, 27, 44, 50, 19];
    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 scores = [11, 11, 17, 15, 11];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  23. 23.🔁 What number does this code show?
    let runs = [89, 48, 87];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  24. 24.🔁 What number does this code show?
    let marks = [19, 4, 10, 10];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  25. 25.🔁 What number does this code show?
    let marks = [17, 20, 1, 20];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  26. 26.🔁 What number does this code show?
    let scores = [57, 89, 88, 17, 72];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  27. 27.🔁 What does a loop do? (a) draws icons (b) saves photos (c) repeats code (d) deletes code
  28. 28.🔁 What number does this code show?
    let runs = [75, 32, 59];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  29. 29.🔁 What number does this code show?
    let runs = [12, 73, 97];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  30. 30.🔁 What number does this code show?
    let scores = [8, 11, 19, 10, 15];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  31. 31.🔁 What number does this code show?
    let runs = [6, 3, 17, 9];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  32. 32.🔁 What number does this code show?
    let runs = [47, 33, 41, 12];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  33. 33.🔁 What number does this code show?
    let marks = [74, 58, 94, 55, 24];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  34. 34.🔁 What number does this code show?
    let runs = [2, 1, 11];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  35. 35.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Arjun", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Kabir (c) Hi, Arjun
  36. 36.🔁 What number does this code show?
    let marks = [54, 48, 73, 87, 37];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  37. 37.🔁 What number does this code show?
    let marks = [8, 9, 7, 3, 20];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  38. 38.🔁 What number does this code show?
    let marks = [11, 15, 1, 18];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  39. 39.🔁 What number does this code show?
    let marks = [6, 12, 13];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  40. 40.🔁 Why use a loop to show 100 messages? (a) it hides them (b) less code to write (c) it is slower (d) it uses more lines

Answer key

  1. 1
  2. 73
  3. 0, 1, 2
  4. 40
  5. 14
  6. 2
  7. 13
  8. how many items it has
  9. 33
  10. 3
  11. 70
  12. 5
  13. 3
  14. 3
  15. Hi, Aman
  16. Hi, Zoya
  17. Hi, Zoya
  18. 3
  19. 14
  20. Hi, Meera
  21. 0
  22. 65
  23. 2
  24. 19
  25. 58
  26. 4
  27. repeats code
  28. 1
  29. 2
  30. 19
  31. 35
  32. 0
  33. 4
  34. 11
  35. Hi, Riya
  36. 4
  37. 20
  38. 18
  39. 13
  40. less code to write

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