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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 624 · 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 scores = [8, 6, 16, 3, 2];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  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 runs = [5, 2, 14, 11];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  4. 4.🔁 What number does this code show?
    let marks = [87, 35, 13, 23];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  5. 5.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Meera", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Kabir (c) Hi, Meera
  6. 6.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 0, 1, 2 (b) 0, 1, 2, 3 (c) 3 (d) 1, 2, 3
  7. 7.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Kabir", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Meera (c) Hi, Riya
  8. 8.🔁 What number does this code show?
    let runs = [14, 1, 8, 16];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  9. 9.🔁 What number does this code show?
    let marks = [61, 39, 87];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  10. 10.🔁 What number does this code show?
    let steps = [58, 97, 22, 10];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  11. 11.🔁 What number does this code show?
    let steps = [2, 16, 16];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  12. 12.🔁 What number does this code show?
    let steps = [6, 18, 19, 6, 16];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  13. 13.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Zoya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Riya (c) Hi, Aman
  14. 14.🔁 What number does this code show?
    let runs = [11, 3, 19, 5];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  15. 15.🔁 What number does this code show?
    let marks = [2, 11, 8];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  16. 16.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Zoya", "Riya", "Kabir", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Riya (c) Hi, Zoya (d) Hi, Aman
  17. 17.🔁 What number does this code show?
    let scores = [2, 2, 16, 4, 12];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  18. 18.🔁 Why use a loop to show 100 messages? (a) it hides them (b) it uses more lines (c) less code to write (d) it is slower
  19. 19.🔁 What number does this code show?
    let scores = [8, 6, 20, 6, 7];
    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 = [25, 57, 83, 78, 49];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  21. 21.🔁 What number does this code show?
    let runs = [5, 1, 5, 9, 6];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  22. 22.🔁 What number does this code show?
    let steps = [15, 6, 9];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  23. 23.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Aman", "Zoya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Arjun (c) Hi, Zoya (d) Hi, Aman
  24. 24.🔁 What number does this code show?
    let runs = [78, 56, 75, 94];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  25. 25.🔁 What number does this code show?
    let marks = [6, 20, 2, 17, 5];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  26. 26.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Kabir", "Riya", "Zoya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Meera (c) Hi, Riya (d) Hi, Kabir
  27. 27.🔁 What number does this code show?
    let steps = [70, 78, 17, 94];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  28. 28.🔁 What number does this code show?
    let marks = [5, 9, 14, 4];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  29. 29.🔁 What number does this code show?
    let scores = [92, 23, 82, 95];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  30. 30.🔁 What number does this code show?
    let scores = [12, 1, 2, 10];
    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 steps = [11, 14, 12, 17];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  32. 32.🔁 What number does this code show?
    let scores = [1, 8, 2, 14];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  33. 33.🔁 What number does this code show?
    let marks = [5, 9, 13, 6];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  34. 34.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Riya", "Zoya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Meera (c) Hi, Arjun (d) Hi, Zoya
  35. 35.🔁 What number does this code show?
    let steps = [17, 2, 11, 18];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  36. 36.🔁 What number does this code show?
    let steps = [12, 2, 4];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  37. 37.🔁 A loop over a list of 5 items runs its body how many times? (a) 6 (b) 4 (c) 5 (d) 1
  38. 38.🔁 What number does this code show?
    let steps = [2, 11, 10, 19, 20];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  39. 39.🔁 list.length tells you ___. (a) the biggest item (b) the last item (c) the first item (d) how many items it has
  40. 40.🔁 What number does this code show?
    let marks = [84, 97, 25, 24];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);

Answer key

  1. 35
  2. repeats code
  3. 14
  4. 1
  5. Hi, Arjun
  6. 0, 1, 2
  7. Hi, Riya
  8. 16
  9. 2
  10. 1
  11. 34
  12. 65
  13. Hi, Aman
  14. 19
  15. 11
  16. Hi, Meera
  17. 16
  18. less code to write
  19. 47
  20. 2
  21. 9
  22. 30
  23. Hi, Arjun
  24. 4
  25. 50
  26. Hi, Aman
  27. 3
  28. 32
  29. 3
  30. 12
  31. 17
  32. 25
  33. 33
  34. Hi, Meera
  35. 48
  36. 18
  37. 5
  38. 62
  39. how many items it has
  40. 2

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