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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 342 · 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 = [11, 20, 5, 16];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  2. 2.🔁 A loop over a list of 5 items runs its body how many times? (a) 5 (b) 1 (c) 6 (d) 4
  3. 3.🔁 What does a loop do? (a) saves photos (b) deletes code (c) draws icons (d) repeats code
  4. 4.🔁 What number does this code show?
    let scores = [75, 45, 22];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  5. 5.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 0, 1, 2, 3 (b) 3 (c) 0, 1, 2 (d) 1, 2, 3
  6. 6.🔁 What number does this code show?
    let steps = [97, 31, 30, 54];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  7. 7.🔁 What number does this code show?
    let scores = [5, 18, 12, 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 runs = [92, 72, 54, 54, 63];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  9. 9.🔁 What number does this code show?
    let scores = [13, 2, 4, 4, 17];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  10. 10.🔁 What number does this code show?
    let steps = [12, 10, 15, 13];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  11. 11.🔁 What number does this code show?
    let runs = [56, 11, 19];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  12. 12.🔁 list.length tells you ___. (a) how many items it has (b) the last item (c) the biggest item (d) the first item
  13. 13.🔁 Why use a loop to show 100 messages? (a) it hides them (b) it uses more lines (c) it is slower (d) less code to write
  14. 14.🔁 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
  15. 15.🔁 What number does this code show?
    let scores = [17, 6, 19];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  16. 16.🔁 What number does this code show?
    let scores = [10, 73, 89, 91];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  17. 17.🔁 What number does this code show?
    let runs = [6, 17, 9];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  18. 18.🔁 What number does this code show?
    let steps = [3, 15, 13, 18, 6];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  19. 19.🔁 What number does this code show?
    let marks = [12, 14, 2, 20];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  20. 20.🔁 What number does this code show?
    let steps = [8, 20, 15];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  21. 21.🔁 What number does this code show?
    let runs = [14, 20, 12];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  22. 22.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Aman", "Meera", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Meera (c) Hi, Riya (d) Hi, Zoya
  23. 23.🔁 What number does this code show?
    let marks = [15, 4, 1, 5];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  24. 24.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Aman", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Zoya (c) Hi, Meera (d) Hi, Riya
  25. 25.🔁 What number does this code show?
    let runs = [39, 76, 82, 87, 20];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  26. 26.🔁 What number does this code show?
    let steps = [3, 11, 15];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  27. 27.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Zoya", "Kabir", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Kabir (c) Hi, Meera (d) Hi, Riya
  28. 28.🔁 What number does this code show?
    let runs = [3, 2, 18];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  29. 29.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Zoya", "Aman", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Aman (c) Hi, Riya (d) Hi, Zoya
  30. 30.🔁 What number does this code show?
    let marks = [14, 7, 17];
    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 = [5, 14, 2, 6];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  32. 32.🔁 What number does this code show?
    let scores = [69, 56, 84];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  33. 33.🔁 What number does this code show?
    let scores = [2, 4, 3];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  34. 34.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Aman", "Riya", "Meera", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Aman (c) Hi, Riya (d) Hi, Kabir
  35. 35.🔁 What number does this code show?
    let marks = [10, 20, 7, 5, 6];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  36. 36.🔁 What number does this code show?
    let marks = [9, 5, 8, 18];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  37. 37.🔁 What number does this code show?
    let marks = [73, 84, 25];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  38. 38.🔁 What number does this code show?
    let scores = [18, 4, 2];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  39. 39.🔁 What number does this code show?
    let scores = [86, 98, 32, 35];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  40. 40.🔁 What number does this code show?
    let marks = [48, 95, 16, 65];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);

Answer key

  1. 52
  2. 5
  3. repeats code
  4. 2
  5. 0, 1, 2
  6. 2
  7. 54
  8. 2
  9. 40
  10. 15
  11. 0
  12. how many items it has
  13. less code to write
  14. Hi, Riya
  15. 42
  16. 3
  17. 32
  18. 55
  19. 48
  20. 20
  21. 20
  22. Hi, Riya
  23. 25
  24. Hi, Meera
  25. 3
  26. 15
  27. Hi, Meera
  28. 23
  29. Hi, Riya
  30. 17
  31. 27
  32. 3
  33. 9
  34. Hi, Kabir
  35. 48
  36. 18
  37. 2
  38. 24
  39. 2
  40. 3

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