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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 774 · 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 = [11, 4, 14];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  2. 2.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Meera", "Kabir", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Riya (c) Hi, Kabir (d) Hi, Meera
  3. 3.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 0, 1, 2, 3 (b) 0, 1, 2 (c) 1, 2, 3 (d) 3
  4. 4.🔁 What number does this code show?
    let marks = [1, 7, 2, 18, 3];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  5. 5.🔁 What number does this code show?
    let runs = [19, 17, 15, 18];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  6. 6.🔁 What number does this code show?
    let scores = [40, 93, 27];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  7. 7.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Zoya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Zoya (c) Hi, Kabir
  8. 8.🔁 What number does this code show?
    let scores = [71, 42, 62, 17, 21];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  9. 9.🔁 What does a loop do? (a) deletes code (b) saves photos (c) draws icons (d) repeats code
  10. 10.🔁 What number does this code show?
    let marks = [72, 94, 94, 56];
    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 scores = [82, 79, 53, 20, 15];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  12. 12.🔁 What number does this code show?
    let scores = [18, 7, 10];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  13. 13.🔁 list.length tells you ___. (a) the biggest item (b) the last item (c) the first item (d) how many items it has
  14. 14.🔁 What number does this code show?
    let marks = [26, 23, 64];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  15. 15.🔁 What number does this code show?
    let steps = [2, 5, 2, 8, 3];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  16. 16.🔁 What number does this code show?
    let runs = [2, 4, 20, 3, 15];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  17. 17.🔁 A loop over a list of 5 items runs its body how many times? (a) 6 (b) 1 (c) 4 (d) 5
  18. 18.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Riya", "Zoya", "Kabir", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Aman (c) Hi, Zoya (d) Hi, Riya
  19. 19.🔁 What number does this code show?
    let scores = [19, 10, 6, 11, 11];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  20. 20.🔁 What number does this code show?
    let runs = [10, 2, 17];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  21. 21.🔁 What number does this code show?
    let marks = [21, 13, 17, 85];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  22. 22.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Arjun", "Kabir", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Arjun (c) Hi, Kabir (d) Hi, Riya
  23. 23.🔁 What number does this code show?
    let runs = [3, 10, 8, 12];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  24. 24.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Riya", "Arjun", "Kabir", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Riya (c) Hi, Aman (d) Hi, Arjun
  25. 25.🔁 What number does this code show?
    let runs = [7, 17, 11];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  26. 26.🔁 What number does this code show?
    let runs = [1, 11, 12];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  27. 27.🔁 Why use a loop to show 100 messages? (a) less code to write (b) it uses more lines (c) it hides them (d) it is slower
  28. 28.🔁 What number does this code show?
    let scores = [97, 72, 64, 96, 72];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  29. 29.🔁 What number does this code show?
    let steps = [14, 2, 2, 6];
    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 marks = [24, 15, 91, 80];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  31. 31.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Riya", "Zoya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Riya (c) Hi, Arjun (d) Hi, Zoya
  32. 32.🔁 What number does this code show?
    let scores = [57, 33, 78, 70, 13];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  33. 33.🔁 What number does this code show?
    let runs = [20, 7, 8];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  34. 34.🔁 What number does this code show?
    let steps = [5, 2, 15, 1];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  35. 35.🔁 What number does this code show?
    let steps = [85, 77, 41, 57];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  36. 36.🔁 What number does this code show?
    let runs = [19, 29, 69, 51];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  37. 37.🔁 What number does this code show?
    let marks = [1, 10, 12, 7];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  38. 38.🔁 What number does this code show?
    let scores = [3, 6, 8, 14];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  39. 39.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Zoya", "Aman", "Riya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Meera (c) Hi, Aman (d) Hi, Zoya
  40. 40.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Riya (c) Hi, Zoya

Answer key

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

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