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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 848 · 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 does a loop do? (a) saves photos (b) draws icons (c) deletes code (d) repeats code
  2. 2.🔁 What number does this code show?
    let scores = [13, 6, 16];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  3. 3.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Aman", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Meera (c) Hi, Kabir (d) Hi, Aman
  4. 4.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 3 (b) 0, 1, 2 (c) 1, 2, 3 (d) 0, 1, 2, 3
  5. 5.🔁 What number does this code show?
    let scores = [23, 42, 97, 54];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  6. 6.🔁 What number does this code show?
    let marks = [14, 12, 20, 15];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  7. 7.🔁 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, Aman (b) Hi, Kabir (c) Hi, Arjun (d) Hi, Zoya
  8. 8.🔁 A loop over a list of 5 items runs its body how many times? (a) 1 (b) 5 (c) 6 (d) 4
  9. 9.🔁 What number does this code show?
    let scores = [70, 74, 51, 12];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  10. 10.🔁 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, Meera (b) Hi, Arjun (c) Hi, Kabir
  11. 11.🔁 What number does this code show?
    let scores = [7, 4, 7];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  12. 12.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Zoya", "Kabir", "Meera", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Riya (c) Hi, Kabir (d) Hi, Zoya
  13. 13.🔁 What number does this code show?
    let steps = [4, 17, 8, 7];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  14. 14.🔁 What number does this code show?
    let marks = [15, 14, 9, 13, 1];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  15. 15.🔁 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, Zoya (b) Hi, Kabir (c) Hi, Arjun (d) Hi, Riya
  16. 16.🔁 What number does this code show?
    let steps = [7, 9, 18];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  17. 17.🔁 list.length tells you ___. (a) the biggest item (b) how many items it has (c) the last item (d) the first item
  18. 18.🔁 What number does this code show?
    let scores = [13, 5, 5];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  19. 19.🔁 What number does this code show?
    let scores = [2, 10, 8, 18];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  20. 20.🔁 What number does this code show?
    let marks = [8, 1, 12];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  21. 21.🔁 What number does this code show?
    let scores = [97, 32, 42, 29];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  22. 22.🔁 What number does this code show?
    let marks = [20, 14, 1];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  23. 23.🔁 What number does this code show?
    let runs = [19, 7, 10];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  24. 24.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Meera", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Zoya (c) Hi, Riya
  25. 25.🔁 What number does this code show?
    let marks = [33, 45, 93, 44, 53];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  26. 26.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Zoya", "Meera", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Kabir (c) Hi, Riya (d) Hi, Meera
  27. 27.🔁 What number does this code show?
    let runs = [29, 52, 34];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  28. 28.🔁 What number does this code show?
    let runs = [6, 14, 3, 17, 17];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  29. 29.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Meera", "Kabir", "Arjun", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Meera (c) Hi, Kabir (d) Hi, Riya
  30. 30.🔁 What number does this code show?
    let scores = [19, 1, 1, 5, 11];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  31. 31.🔁 What number does this code show?
    let scores = [16, 85, 47, 12];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  32. 32.🔁 What number does this code show?
    let scores = [14, 4, 4, 4, 2];
    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 runs = [7, 9, 9, 16];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  34. 34.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Arjun", "Meera", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Zoya (c) Hi, Arjun (d) Hi, Kabir
  35. 35.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Meera", "Kabir", "Arjun", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Kabir (c) Hi, Riya (d) Hi, Meera
  36. 36.🔁 Why use a loop to show 100 messages? (a) it uses more lines (b) less code to write (c) it is slower (d) it hides them
  37. 37.🔁 What number does this code show?
    let steps = [98, 59, 44];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  38. 38.🔁 What number does this code show?
    let runs = [7, 3, 3, 15, 16];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  39. 39.🔁 What number does this code show?
    let scores = [70, 85, 99, 93];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  40. 40.🔁 What number does this code show?
    let marks = [17, 1, 12, 12];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);

Answer key

  1. repeats code
  2. 35
  3. Hi, Kabir
  4. 0, 1, 2
  5. 2
  6. 61
  7. Hi, Kabir
  8. 5
  9. 3
  10. Hi, Arjun
  11. 7
  12. Hi, Arjun
  13. 17
  14. 15
  15. Hi, Arjun
  16. 34
  17. how many items it has
  18. 23
  19. 18
  20. 21
  21. 1
  22. 20
  23. 19
  24. Hi, Riya
  25. 4
  26. Hi, Riya
  27. 1
  28. 17
  29. Hi, Riya
  30. 37
  31. 2
  32. 28
  33. 16
  34. Hi, Zoya
  35. Hi, Riya
  36. less code to write
  37. 3
  38. 44
  39. 4
  40. 17

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