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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 737 · 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.🔁 list.length tells you ___. (a) the first item (b) the biggest item (c) how many items it has (d) the last item
  2. 2.🔁 What number does this code show?
    let marks = [11, 11, 6, 11];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  3. 3.🔁 What number does this code show?
    let runs = [18, 5, 7, 6, 14];
    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 scores = [4, 10, 1, 3, 10];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  5. 5.🔁 What number does this code show?
    let scores = [14, 13, 13];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  6. 6.🔁 What number does this code show?
    let runs = [64, 12, 72, 60];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  7. 7.🔁 What number does this code show?
    let scores = [12, 12, 4, 10, 9];
    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 scores = [77, 80, 46, 98, 74];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  9. 9.🔁 What number does this code show?
    let steps = [75, 92, 33];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  10. 10.🔁 Why use a loop to show 100 messages? (a) less code to write (b) it hides them (c) it uses more lines (d) it is slower
  11. 11.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 1, 2, 3 (b) 0, 1, 2, 3 (c) 3 (d) 0, 1, 2
  12. 12.🔁 What number does this code show?
    let scores = [14, 14, 9];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  13. 13.🔁 A loop over a list of 5 items runs its body how many times? (a) 6 (b) 1 (c) 4 (d) 5
  14. 14.🔁 What number does this code show?
    let scores = [9, 8, 18];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  15. 15.🔁 What does a loop do? (a) draws icons (b) saves photos (c) repeats code (d) deletes code
  16. 16.🔁 What number does this code show?
    let runs = [65, 25, 98, 85, 34];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  17. 17.🔁 What number does this code show?
    let steps = [38, 11, 66];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  18. 18.🔁 What number does this code show?
    let scores = [2, 5, 20];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  19. 19.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Arjun", "Zoya", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Riya (c) Hi, Aman (d) Hi, Zoya
  20. 20.🔁 What number does this code show?
    let marks = [10, 4, 10, 3, 8];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  21. 21.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Kabir", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Kabir (c) Hi, Arjun
  22. 22.🔁 What number does this code show?
    let steps = [20, 3, 1, 6, 13];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  23. 23.🔁 What number does this code show?
    let steps = [26, 24, 45, 43, 98];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  24. 24.🔁 What number does this code show?
    let steps = [2, 11, 13];
    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 = [20, 17, 14, 5];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  26. 26.🔁 What number does this code show?
    let marks = [16, 20, 1];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  27. 27.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Aman", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Kabir (c) Hi, Riya
  28. 28.🔁 What number does this code show?
    let steps = [15, 19, 20, 19];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  29. 29.🔁 What number does this code show?
    let runs = [10, 3, 6, 5, 4];
    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 runs = [13, 10, 16, 15, 11];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  31. 31.🔁 What number does this code show?
    let marks = [11, 6, 17, 5, 8];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  32. 32.🔁 What number does this code show?
    let marks = [13, 20, 1, 3];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  33. 33.🔁 What number does this code show?
    let runs = [16, 8, 14, 14, 3];
    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 = ["Aman", "Meera", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Zoya (c) Hi, Meera
  35. 35.🔁 What number does this code show?
    let marks = [30, 38, 90, 57];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  36. 36.🔁 What number does this code show?
    let steps = [6, 17, 7];
    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 = [5, 13, 12, 4];
    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 scores = [73, 26, 90, 48];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  39. 39.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Riya", "Arjun", "Aman", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Kabir (c) Hi, Riya (d) Hi, Arjun
  40. 40.🔁 What number does this code show?
    let marks = [13, 11, 13, 9];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);

Answer key

  1. how many items it has
  2. 11
  3. 50
  4. 28
  5. 14
  6. 1
  7. 47
  8. 5
  9. 2
  10. less code to write
  11. 0, 1, 2
  12. 14
  13. 5
  14. 35
  15. repeats code
  16. 2
  17. 1
  18. 27
  19. Hi, Riya
  20. 10
  21. Hi, Aman
  22. 43
  23. 1
  24. 13
  25. 56
  26. 20
  27. Hi, Kabir
  28. 20
  29. 28
  30. 16
  31. 17
  32. 20
  33. 16
  34. Hi, Zoya
  35. 2
  36. 30
  37. 13
  38. 2
  39. Hi, Kabir
  40. 46

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