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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 151 · 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 = [5, 4, 12, 16];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  2. 2.🔁 What number does this code show?
    let scores = [26, 78, 31];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  3. 3.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Arjun", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Arjun (c) Hi, Zoya (d) Hi, Riya
  4. 4.🔁 What number does this code show?
    let runs = [87, 27, 19, 96, 24];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  5. 5.🔁 A loop over a list of 5 items runs its body how many times? (a) 6 (b) 5 (c) 4 (d) 1
  6. 6.🔁 What number does this code show?
    let marks = [20, 3, 2, 13];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  7. 7.🔁 What number does this code show?
    let marks = [53, 52, 77, 11, 46];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  8. 8.🔁 What number does this code show?
    let steps = [5, 5, 16];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  9. 9.🔁 What number does this code show?
    let steps = [9, 16, 13, 8, 8];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  10. 10.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 3 (b) 1, 2, 3 (c) 0, 1, 2, 3 (d) 0, 1, 2
  11. 11.🔁 What number does this code show?
    let scores = [19, 5, 8, 18, 8];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  12. 12.🔁 What does a loop do? (a) saves photos (b) draws icons (c) repeats code (d) deletes code
  13. 13.🔁 What number does this code show?
    let marks = [93, 25, 18];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  14. 14.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Riya", "Zoya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Zoya (c) Hi, Arjun (d) Hi, Aman
  15. 15.🔁 What number does this code show?
    let steps = [19, 1, 19, 15, 2];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  16. 16.🔁 What number does this code show?
    let scores = [57, 85, 87, 36];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  17. 17.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Aman", "Arjun", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Aman (c) Hi, Zoya (d) Hi, Kabir
  18. 18.🔁 What number does this code show?
    let marks = [42, 16, 81];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  19. 19.🔁 What number does this code show?
    let steps = [13, 8, 15, 7, 14];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  20. 20.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Arjun", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Arjun (c) Hi, Aman
  21. 21.🔁 What number does this code show?
    let marks = [17, 76, 79];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  22. 22.🔁 What number does this code show?
    let steps = [11, 15, 9, 7];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  23. 23.🔁 What number does this code show?
    let marks = [11, 19, 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 = [20, 11, 2];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  25. 25.🔁 Why use a loop to show 100 messages? (a) it is slower (b) it hides them (c) it uses more lines (d) less code to write
  26. 26.🔁 What number does this code show?
    let steps = [23, 39, 84, 51];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  27. 27.🔁 What number does this code show?
    let marks = [90, 51, 76, 28, 99];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  28. 28.🔁 What number does this code show?
    let steps = [2, 4, 2, 17, 6];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  29. 29.🔁 What number does this code show?
    let runs = [89, 31, 48, 23];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  30. 30.🔁 What number does this code show?
    let scores = [11, 5, 1, 15, 18];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  31. 31.🔁 What number does this code show?
    let scores = [13, 9, 4, 10, 5];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  32. 32.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Meera", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Meera (c) Hi, Arjun
  33. 33.🔁 What number does this code show?
    let steps = [1, 1, 20];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  34. 34.🔁 What number does this code show?
    let steps = [17, 5, 17, 5];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  35. 35.🔁 What number does this code show?
    let marks = [6, 9, 14, 15];
    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 runs = [9, 15, 3];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  37. 37.🔁 What number does this code show?
    let runs = [14, 39, 38, 98, 77];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  38. 38.🔁 What number does this code show?
    let runs = [3, 3, 4];
    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 = ["Riya", "Kabir", "Aman", "Arjun", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Aman (c) Hi, Kabir (d) Hi, Meera
  40. 40.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Zoya", "Aman", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Kabir (c) Hi, Zoya (d) Hi, Riya

Answer key

  1. 37
  2. 1
  3. Hi, Kabir
  4. 2
  5. 5
  6. 20
  7. 4
  8. 16
  9. 16
  10. 0, 1, 2
  11. 58
  12. repeats code
  13. 1
  14. Hi, Aman
  15. 19
  16. 3
  17. Hi, Zoya
  18. 1
  19. 15
  20. Hi, Kabir
  21. 2
  22. 15
  23. 19
  24. 20
  25. less code to write
  26. 2
  27. 4
  28. 17
  29. 1
  30. 18
  31. 41
  32. Hi, Zoya
  33. 20
  34. 44
  35. 44
  36. 15
  37. 2
  38. 4
  39. Hi, Meera
  40. Hi, Arjun

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