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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 701 · 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 = [2, 5, 3, 11, 8];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  2. 2.🔁 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
  3. 3.🔁 What number does this code show?
    let scores = [2, 20, 9, 16, 6];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  4. 4.🔁 What number does this code show?
    let runs = [46, 26, 81, 76, 71];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  5. 5.🔁 What number does this code show?
    let steps = [83, 30, 38];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  6. 6.🔁 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, Zoya (b) Hi, Riya (c) Hi, Kabir
  7. 7.🔁 What number does this code show?
    let scores = [19, 10, 17, 13];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  8. 8.🔁 What number does this code show?
    let scores = [19, 5, 3];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  9. 9.🔁 What number does this code show?
    let steps = [68, 87, 28, 90];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  10. 10.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Aman", "Arjun", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Aman (c) Hi, Zoya (d) Hi, Kabir
  11. 11.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Meera", "Riya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Riya (c) Hi, Aman (d) Hi, Meera
  12. 12.🔁 What number does this code show?
    let scores = [12, 6, 16, 15, 9];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  13. 13.🔁 What number does this code show?
    let steps = [4, 9, 16];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  14. 14.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Kabir", "Aman", "Arjun", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Kabir (c) Hi, Meera (d) Hi, Zoya
  15. 15.🔁 What does a loop do? (a) draws icons (b) deletes code (c) repeats code (d) saves photos
  16. 16.🔁 What number does this code show?
    let scores = [86, 68, 97];
    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 = [7, 13, 15, 19];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  18. 18.🔁 What number does this code show?
    let marks = [11, 19, 11];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  19. 19.🔁 What number does this code show?
    let runs = [16, 7, 14, 20, 3];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  20. 20.🔁 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, Kabir (b) Hi, Riya (c) Hi, Arjun
  21. 21.🔁 What number does this code show?
    let steps = [15, 14, 17];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  22. 22.🔁 What number does this code show?
    let steps = [89, 94, 33];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  23. 23.🔁 What number does this code show?
    let runs = [25, 97, 15];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  24. 24.🔁 What number does this code show?
    let runs = [8, 15, 2, 10];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  25. 25.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 0, 1, 2, 3 (b) 0, 1, 2 (c) 3 (d) 1, 2, 3
  26. 26.🔁 What number does this code show?
    let scores = [10, 18, 9, 13, 14];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  27. 27.🔁 What number does this code show?
    let scores = [11, 9, 13];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  28. 28.🔁 list.length tells you ___. (a) how many items it has (b) the last item (c) the biggest item (d) the first item
  29. 29.🔁 What number does this code show?
    let marks = [9, 8, 16];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  30. 30.🔁 What number does this code show?
    let scores = [5, 18, 18];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  31. 31.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Aman", "Kabir", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Aman (c) Hi, Arjun (d) Hi, Kabir
  32. 32.🔁 What number does this code show?
    let steps = [9, 11, 4, 12, 12];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  33. 33.🔁 What number does this code show?
    let steps = [61, 14, 48];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  34. 34.🔁 What number does this code show?
    let steps = [45, 49, 83];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  35. 35.🔁 What number does this code show?
    let marks = [11, 16, 19];
    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 scores = [44, 33, 11, 63, 38];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  37. 37.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Arjun", "Zoya", "Aman", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Kabir (c) Hi, Riya (d) Hi, Arjun
  38. 38.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Kabir", "Aman", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Riya (c) Hi, Meera (d) Hi, Aman
  39. 39.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Kabir", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Meera (c) Hi, Kabir
  40. 40.🔁 What number does this code show?
    let marks = [19, 5, 17, 7, 7];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);

Answer key

  1. 11
  2. less code to write
  3. 20
  4. 4
  5. 1
  6. Hi, Kabir
  7. 19
  8. 27
  9. 3
  10. Hi, Kabir
  11. Hi, Arjun
  12. 16
  13. 29
  14. Hi, Meera
  15. repeats code
  16. 3
  17. 19
  18. 19
  19. 60
  20. Hi, Riya
  21. 46
  22. 2
  23. 1
  24. 35
  25. 0, 1, 2
  26. 18
  27. 13
  28. how many items it has
  29. 33
  30. 18
  31. Hi, Arjun
  32. 12
  33. 1
  34. 1
  35. 46
  36. 1
  37. Hi, Riya
  38. Hi, Riya
  39. Hi, Meera
  40. 55

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