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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 582 · 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 = [16, 19, 3];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  2. 2.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Kabir", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Arjun (c) Hi, Kabir
  3. 3.🔁 What number does this code show?
    let steps = [3, 14, 20, 12, 8];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  4. 4.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Meera (c) Hi, Riya
  5. 5.🔁 What number does this code show?
    let marks = [79, 11, 88, 40];
    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 runs = [36, 91, 74, 17];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  7. 7.🔁 What number does this code show?
    let scores = [44, 23, 90, 49];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  8. 8.🔁 What does a loop do? (a) repeats code (b) deletes code (c) saves photos (d) draws icons
  9. 9.🔁 list.length tells you ___. (a) the biggest item (b) how many items it has (c) the last item (d) the first item
  10. 10.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Arjun", "Aman", "Kabir", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Riya (c) Hi, Arjun (d) Hi, Zoya
  11. 11.🔁 What number does this code show?
    let marks = [18, 16, 8];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  12. 12.🔁 What number does this code show?
    let steps = [18, 3, 19];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  13. 13.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 3 (b) 1, 2, 3 (c) 0, 1, 2 (d) 0, 1, 2, 3
  14. 14.🔁 What number does this code show?
    let runs = [13, 17, 10];
    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 = [77, 63, 79, 26];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  16. 16.🔁 What number does this code show?
    let runs = [2, 20, 5, 18];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  17. 17.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Kabir", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Zoya (c) Hi, Arjun (d) Hi, Riya
  18. 18.🔁 What number does this code show?
    let marks = [5, 14, 5, 14, 10];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  19. 19.🔁 What number does this code show?
    let steps = [5, 10, 15];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  20. 20.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Zoya", "Riya", "Kabir", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Meera (c) Hi, Aman (d) Hi, Riya
  21. 21.🔁 What number does this code show?
    let steps = [8, 1, 2];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  22. 22.🔁 What number does this code show?
    let steps = [57, 80, 87, 61];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  23. 23.🔁 What number does this code show?
    let marks = [4, 5, 6];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  24. 24.🔁 What number does this code show?
    let runs = [15, 5, 3, 1, 5];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  25. 25.🔁 What number does this code show?
    let scores = [79, 28, 46];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  26. 26.🔁 What number does this code show?
    let runs = [19, 12, 1];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  27. 27.🔁 Why use a loop to show 100 messages? (a) it is slower (b) it uses more lines (c) it hides them (d) less code to write
  28. 28.🔁 What number does this code show?
    let marks = [1, 2, 1, 16];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  29. 29.🔁 What number does this code show?
    let scores = [15, 9, 2, 16];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  30. 30.🔁 What number does this code show?
    let steps = [3, 4, 7];
    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 steps = [57, 87, 69, 69];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  32. 32.🔁 What number does this code show?
    let scores = [32, 97, 22];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  33. 33.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Riya (c) Hi, Kabir
  34. 34.🔁 What number does this code show?
    let scores = [5, 4, 12, 11];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  35. 35.🔁 What number does this code show?
    let steps = [85, 82, 76, 79, 27];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  36. 36.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Zoya", "Kabir", "Meera", "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
  37. 37.🔁 What number does this code show?
    let runs = [14, 32, 87, 53];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  38. 38.🔁 What number does this code show?
    let runs = [15, 20, 1, 12];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  39. 39.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Aman", "Meera", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Zoya (c) Hi, Aman (d) Hi, Kabir
  40. 40.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Kabir", "Aman", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Meera (c) Hi, Arjun (d) Hi, Aman

Answer key

  1. 19
  2. Hi, Arjun
  3. 57
  4. Hi, Zoya
  5. 2
  6. 2
  7. 1
  8. repeats code
  9. how many items it has
  10. Hi, Zoya
  11. 42
  12. 19
  13. 0, 1, 2
  14. 17
  15. 2
  16. 45
  17. Hi, Arjun
  18. 48
  19. 30
  20. Hi, Aman
  21. 8
  22. 4
  23. 6
  24. 29
  25. 1
  26. 19
  27. less code to write
  28. 16
  29. 42
  30. 7
  31. 4
  32. 1
  33. Hi, Arjun
  34. 12
  35. 4
  36. Hi, Riya
  37. 1
  38. 20
  39. Hi, Zoya
  40. Hi, Meera

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