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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 25 · 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.🔁 list.length tells you ___. (a) how many items it has (b) the biggest item (c) the last item (d) the first item
  2. 2.🔁 What number does this code show?
    let steps = [7, 7, 2, 12];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  3. 3.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Arjun", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Aman (c) Hi, Arjun
  4. 4.🔁 What does a loop do? (a) repeats code (b) deletes code (c) draws icons (d) saves photos
  5. 5.🔁 What number does this code show?
    let steps = [20, 1, 11];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  6. 6.🔁 Why use a loop to show 100 messages? (a) it hides them (b) it is slower (c) less code to write (d) it uses more lines
  7. 7.🔁 What number does this code show?
    let steps = [19, 20, 7, 17, 17];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  8. 8.🔁 What number does this code show?
    let runs = [5, 3, 3, 20, 14];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  9. 9.🔁 What number does this code show?
    let runs = [90, 38, 16];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  10. 10.🔁 What number does this code show?
    let runs = [25, 53, 95];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  11. 11.🔁 What number does this code show?
    let scores = [11, 13, 18, 16];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  12. 12.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 1, 2, 3 (b) 0, 1, 2, 3 (c) 3 (d) 0, 1, 2
  13. 13.🔁 A loop over a list of 5 items runs its body how many times? (a) 6 (b) 5 (c) 1 (d) 4
  14. 14.🔁 What number does this code show?
    let scores = [1, 15, 8];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  15. 15.🔁 What number does this code show?
    let steps = [32, 38, 51, 24, 58];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  16. 16.🔁 What number does this code show?
    let steps = [1, 11, 1];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  17. 17.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Arjun", "Aman", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Arjun (c) Hi, Kabir (d) Hi, Riya
  18. 18.🔁 What number does this code show?
    let runs = [92, 77, 31, 74, 88];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  19. 19.🔁 What number does this code show?
    let marks = [86, 41, 46, 40];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  20. 20.🔁 What number does this code show?
    let marks = [10, 88, 37, 22, 13];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  21. 21.🔁 What number does this code show?
    let scores = [2, 20, 6, 13, 2];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  22. 22.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Aman", "Arjun", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Arjun (c) Hi, Meera (d) Hi, Aman
  23. 23.🔁 What number does this code show?
    let scores = [4, 2, 4, 12];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  24. 24.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Aman (c) Hi, Riya
  25. 25.🔁 What number does this code show?
    let marks = [65, 15, 65, 19];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  26. 26.🔁 What number does this code show?
    let runs = [16, 19, 4];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  27. 27.🔁 What number does this code show?
    let marks = [6, 8, 11, 15, 13];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  28. 28.🔁 What number does this code show?
    let steps = [2, 1, 4, 8, 13];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  29. 29.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Aman", "Kabir", "Arjun", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Zoya (c) Hi, Riya (d) Hi, Aman
  30. 30.🔁 What number does this code show?
    let marks = [3, 20, 5, 1];
    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 = [27, 37, 26];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  32. 32.🔁 What number does this code show?
    let marks = [10, 3, 18, 5, 3];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  33. 33.🔁 What number does this code show?
    let marks = [2, 20, 20];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  34. 34.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Kabir", "Arjun", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Meera (c) Hi, Arjun (d) Hi, Aman
  35. 35.🔁 What number does this code show?
    let scores = [17, 10, 4];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  36. 36.🔁 What number does this code show?
    let runs = [17, 10, 9, 18];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  37. 37.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Arjun", "Kabir", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Zoya (c) Hi, Kabir (d) Hi, Arjun
  38. 38.🔁 What number does this code show?
    let scores = [29, 38, 18, 77, 94];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  39. 39.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Aman", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Kabir (c) Hi, Aman
  40. 40.🔁 What number does this code show?
    let runs = [5, 17, 4];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);

Answer key

  1. how many items it has
  2. 28
  3. Hi, Aman
  4. repeats code
  5. 20
  6. less code to write
  7. 20
  8. 45
  9. 1
  10. 2
  11. 58
  12. 0, 1, 2
  13. 5
  14. 15
  15. 2
  16. 13
  17. Hi, Kabir
  18. 4
  19. 4
  20. 1
  21. 43
  22. Hi, Zoya
  23. 22
  24. Hi, Meera
  25. 2
  26. 39
  27. 15
  28. 13
  29. Hi, Riya
  30. 20
  31. 0
  32. 18
  33. 20
  34. Hi, Aman
  35. 17
  36. 54
  37. Hi, Zoya
  38. 2
  39. Hi, Riya
  40. 17

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