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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 488 · 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 = [8, 20, 5, 18, 6];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  2. 2.🔁 What does a loop do? (a) deletes code (b) saves photos (c) draws icons (d) repeats code
  3. 3.🔁 What number does this code show?
    let scores = [34, 28, 35, 75, 48];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  4. 4.🔁 A loop over a list of 5 items runs its body how many times? (a) 6 (b) 4 (c) 1 (d) 5
  5. 5.🔁 Why use a loop to show 100 messages? (a) it uses more lines (b) it hides them (c) less code to write (d) it is slower
  6. 6.🔁 What number does this code show?
    let scores = [62, 50, 27, 29, 27];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  7. 7.🔁 What number does this code show?
    let marks = [6, 14, 1];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  8. 8.🔁 What number does this code show?
    let marks = [18, 10, 13, 1, 5];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  9. 9.🔁 What number does this code show?
    let marks = [19, 3, 8];
    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 = [11, 17, 3, 16, 14];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  11. 11.🔁 What number does this code show?
    let marks = [8, 7, 6, 6, 18];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  12. 12.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Arjun", "Kabir", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Aman (c) Hi, Kabir (d) Hi, Arjun
  13. 13.🔁 What number does this code show?
    let runs = [3, 2, 12, 14];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  14. 14.🔁 What number does this code show?
    let marks = [36, 28, 81, 99, 10];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  15. 15.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Arjun", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Meera (c) Hi, Kabir
  16. 16.🔁 What number does this code show?
    let steps = [11, 12, 8];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  17. 17.🔁 What number does this code show?
    let marks = [6, 17, 1, 11];
    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 scores = [16, 16, 12, 18, 7];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  19. 19.🔁 What number does this code show?
    let runs = [64, 80, 88];
    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 = [20, 2, 2, 20];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  21. 21.🔁 list.length tells you ___. (a) the biggest item (b) the last item (c) the first item (d) how many items it has
  22. 22.🔁 What number does this code show?
    let marks = [6, 6, 15];
    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 = [28, 98, 72, 84];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  24. 24.🔁 What number does this code show?
    let scores = [12, 15, 10];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  25. 25.🔁 What number does this code show?
    let runs = [1, 15, 12, 2, 15];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  26. 26.🔁 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
  27. 27.🔁 What number does this code show?
    let steps = [14, 10, 13, 9];
    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 runs = [11, 19, 9, 16, 16];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  29. 29.🔁 What number does this code show?
    let marks = [69, 79, 74, 38, 43];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  30. 30.🔁 What number does this code show?
    let marks = [17, 7, 8, 5];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  31. 31.🔁 What number does this code show?
    let scores = [2, 9, 11, 18, 3];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  32. 32.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Kabir", "Zoya", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Zoya (c) Hi, Aman (d) Hi, Kabir
  33. 33.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Kabir (c) Hi, Aman
  34. 34.🔁 What number does this code show?
    let steps = [57, 67, 18, 75, 38];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  35. 35.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Meera (c) Hi, Riya
  36. 36.🔁 What number does this code show?
    let steps = [61, 34, 12];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  37. 37.🔁 What number does this code show?
    let marks = [7, 16, 11];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  38. 38.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Meera", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Meera (c) Hi, Aman
  39. 39.🔁 What number does this code show?
    let marks = [18, 1, 17, 6];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  40. 40.🔁 What number does this code show?
    let scores = [68, 96, 27, 76];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);

Answer key

  1. 20
  2. repeats code
  3. 1
  4. 5
  5. less code to write
  6. 0
  7. 14
  8. 18
  9. 30
  10. 17
  11. 45
  12. Hi, Aman
  13. 14
  14. 2
  15. Hi, Meera
  16. 12
  17. 35
  18. 18
  19. 3
  20. 44
  21. how many items it has
  22. 27
  23. 3
  24. 15
  25. 15
  26. 0, 1, 2
  27. 14
  28. 19
  29. 4
  30. 17
  31. 18
  32. Hi, Meera
  33. Hi, Kabir
  34. 3
  35. Hi, Arjun
  36. 0
  37. 34
  38. Hi, Riya
  39. 42
  40. 3

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