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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 642 · 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 = [89, 54, 83, 25];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  2. 2.🔁 What number does this code show?
    let marks = [11, 1, 20, 8, 16];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  3. 3.🔁 What number does this code show?
    let steps = [15, 3, 13, 6];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  4. 4.🔁 Why use a loop to show 100 messages? (a) it hides them (b) less code to write (c) it uses more lines (d) it is slower
  5. 5.🔁 What number does this code show?
    let marks = [20, 13, 11];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  6. 6.🔁 What number does this code show?
    let steps = [12, 17, 7];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  7. 7.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Zoya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Kabir (c) Hi, Aman
  8. 8.🔁 What does a loop do? (a) deletes code (b) repeats code (c) saves photos (d) draws icons
  9. 9.🔁 What number does this code show?
    let steps = [14, 18, 5];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  10. 10.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Aman", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Aman (c) Hi, Kabir
  11. 11.🔁 What number does this code show?
    let marks = [15, 11, 6];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  12. 12.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Kabir", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Kabir (c) Hi, Zoya
  13. 13.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Arjun", "Riya", "Meera", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Aman (c) Hi, Arjun (d) Hi, Riya
  14. 14.🔁 What number does this code show?
    let scores = [42, 54, 22, 88];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  15. 15.🔁 A loop over a list of 5 items runs its body how many times? (a) 4 (b) 6 (c) 1 (d) 5
  16. 16.🔁 What number does this code show?
    let runs = [69, 89, 16];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  17. 17.🔁 What number does this code show?
    let scores = [65, 72, 39, 70, 25];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  18. 18.🔁 What number does this code show?
    let steps = [62, 39, 60];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  19. 19.🔁 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
  20. 20.🔁 What number does this code show?
    let runs = [5, 6, 14, 18];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  21. 21.🔁 What number does this code show?
    let marks = [11, 63, 12];
    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 runs = [3, 11, 3, 17];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  23. 23.🔁 What number does this code show?
    let marks = [9, 19, 3, 3, 2];
    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 scores = [13, 12, 8, 11, 13];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  25. 25.🔁 What number does this code show?
    let steps = [2, 1, 16];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  26. 26.🔁 What number does this code show?
    let marks = [5, 8, 15];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  27. 27.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Arjun", "Zoya", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Arjun (c) Hi, Aman (d) Hi, Zoya
  28. 28.🔁 What number does this code show?
    let steps = [12, 9, 5];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  29. 29.🔁 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, Aman (b) Hi, Kabir (c) Hi, Riya (d) Hi, Arjun
  30. 30.🔁 What number does this code show?
    let steps = [70, 99, 49, 24, 43];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  31. 31.🔁 What number does this code show?
    let scores = [9, 17, 17];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  32. 32.🔁 What number does this code show?
    let marks = [5, 1, 17];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  33. 33.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Riya", "Kabir", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Meera (c) Hi, Riya (d) Hi, Arjun
  34. 34.🔁 What number does this code show?
    let marks = [10, 1, 14, 2];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  35. 35.🔁 What number does this code show?
    let scores = [78, 45, 23];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  36. 36.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Aman", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Arjun (c) Hi, Riya
  37. 37.🔁 What number does this code show?
    let steps = [20, 80, 66, 19, 41];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  38. 38.🔁 What number does this code show?
    let runs = [12, 20, 4, 9];
    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 = [17, 10, 14, 6, 13];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  40. 40.🔁 What number does this code show?
    let scores = [7, 12, 17, 9];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);

Answer key

  1. 2
  2. 20
  3. 15
  4. less code to write
  5. 44
  6. 36
  7. Hi, Aman
  8. repeats code
  9. 18
  10. Hi, Kabir
  11. 15
  12. Hi, Meera
  13. Hi, Kabir
  14. 3
  15. 5
  16. 2
  17. 3
  18. 2
  19. Hi, Riya
  20. 18
  21. 1
  22. 34
  23. 19
  24. 13
  25. 19
  26. 28
  27. Hi, Meera
  28. 26
  29. Hi, Arjun
  30. 4
  31. 43
  32. 23
  33. Hi, Meera
  34. 27
  35. 2
  36. Hi, Riya
  37. 2
  38. 45
  39. 60
  40. 45

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