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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 490 · 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 = [36, 75, 11, 83];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  2. 2.🔁 What does a loop do? (a) saves photos (b) draws icons (c) deletes code (d) repeats code
  3. 3.🔁 What number does this code show?
    let steps = [17, 8, 18, 11];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  4. 4.🔁 Why use a loop to show 100 messages? (a) it hides them (b) less code to write (c) it is slower (d) it uses more lines
  5. 5.🔁 What number does this code show?
    let marks = [31, 21, 52, 41, 21];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  6. 6.🔁 What number does this code show?
    let marks = [39, 89, 13];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  7. 7.🔁 What number does this code show?
    let scores = [20, 2, 8, 7];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  8. 8.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Arjun", "Zoya", "Kabir", "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
  9. 9.🔁 What number does this code show?
    let marks = [62, 87, 80];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  10. 10.🔁 list.length tells you ___. (a) the last item (b) the biggest item (c) the first item (d) how many items it has
  11. 11.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Aman", "Zoya", "Meera", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Zoya (c) Hi, Arjun (d) Hi, Riya
  12. 12.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Aman", "Kabir", "Riya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Kabir (c) Hi, Aman (d) Hi, Zoya
  13. 13.🔁 What number does this code show?
    let steps = [54, 63, 69, 36, 71];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  14. 14.🔁 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
  15. 15.🔁 What number does this code show?
    let scores = [53, 40, 74];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  16. 16.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Zoya", "Riya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Aman (c) Hi, Zoya (d) Hi, Arjun
  17. 17.🔁 What number does this code show?
    let scores = [13, 4, 16, 2, 9];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  18. 18.🔁 A loop over a list of 5 items runs its body how many times? (a) 6 (b) 1 (c) 4 (d) 5
  19. 19.🔁 What number does this code show?
    let steps = [12, 9, 4, 7];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  20. 20.🔁 What number does this code show?
    let steps = [18, 15, 2, 11, 1];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  21. 21.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Zoya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Zoya (c) Hi, Meera
  22. 22.🔁 What number does this code show?
    let marks = [72, 88, 77, 50];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  23. 23.🔁 What number does this code show?
    let marks = [6, 7, 10, 11];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  24. 24.🔁 What number does this code show?
    let steps = [6, 4, 7, 15];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  25. 25.🔁 What number does this code show?
    let scores = [11, 17, 5, 9];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  26. 26.🔁 What number does this code show?
    let scores = [25, 20, 47];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  27. 27.🔁 What number does this code show?
    let scores = [3, 13, 20];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  28. 28.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Riya (c) Hi, Meera
  29. 29.🔁 What number does this code show?
    let marks = [98, 12, 25, 25, 56];
    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 steps = [1, 1, 8];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  31. 31.🔁 What number does this code show?
    let runs = [5, 17, 4];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  32. 32.🔁 What number does this code show?
    let marks = [17, 9, 6];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  33. 33.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Aman", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Arjun (c) Hi, Aman
  34. 34.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Aman", "Zoya", "Arjun", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Aman (c) Hi, Kabir (d) Hi, Zoya
  35. 35.🔁 What number does this code show?
    let steps = [58, 48, 32];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  36. 36.🔁 What number does this code show?
    let scores = [98, 56, 81, 39, 63];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  37. 37.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Kabir", "Riya", "Arjun", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Riya (c) Hi, Kabir (d) Hi, Aman
  38. 38.🔁 What number does this code show?
    let scores = [43, 42, 60, 29];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  39. 39.🔁 What number does this code show?
    let scores = [5, 8, 13, 2, 14];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  40. 40.🔁 What number does this code show?
    let marks = [9, 3, 12];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);

Answer key

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

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