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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 122 · 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 scores = [65, 22, 21];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  2. 2.🔁 What number does this code show?
    let marks = [4, 18, 11];
    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 scores = [41, 35, 35, 26];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  4. 4.🔁 A loop over a list of 5 items runs its body how many times? (a) 5 (b) 4 (c) 6 (d) 1
  5. 5.🔁 What number does this code show?
    let runs = [13, 5, 18];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  6. 6.🔁 What number does this code show?
    let scores = [17, 19, 18];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  7. 7.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Aman", "Meera", "Zoya", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Riya (c) Hi, Aman (d) Hi, Meera
  8. 8.🔁 What number does this code show?
    let steps = [18, 9, 4, 5];
    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 runs = [20, 14, 4];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  10. 10.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Aman", "Kabir", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Aman (c) Hi, Zoya (d) Hi, Kabir
  11. 11.🔁 What does a loop do? (a) deletes code (b) repeats code (c) draws icons (d) saves photos
  12. 12.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Arjun", "Aman", "Kabir", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Meera (c) Hi, Riya (d) Hi, Aman
  13. 13.🔁 Why use a loop to show 100 messages? (a) less code to write (b) it is slower (c) it uses more lines (d) it hides them
  14. 14.🔁 What number does this code show?
    let scores = [7, 3, 3, 1];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  15. 15.🔁 What number does this code show?
    let scores = [41, 60, 69];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  16. 16.🔁 What number does this code show?
    let runs = [13, 7, 2, 3];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  17. 17.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Kabir", "Meera", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Kabir (c) Hi, Meera (d) Hi, Arjun
  18. 18.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Arjun", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Arjun (c) Hi, Meera (d) Hi, Riya
  19. 19.🔁 What number does this code show?
    let steps = [36, 66, 55, 25];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  20. 20.🔁 What number does this code show?
    let marks = [51, 50, 20, 43];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  21. 21.🔁 list.length tells you ___. (a) the first item (b) the last item (c) how many items it has (d) the biggest item
  22. 22.🔁 What number does this code show?
    let marks = [12, 4, 5];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  23. 23.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Meera", "Kabir", "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
  24. 24.🔁 What number does this code show?
    let runs = [17, 8, 17];
    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 marks = [10, 1, 5];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  26. 26.🔁 What number does this code show?
    let steps = [5, 16, 20];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  27. 27.🔁 What number does this code show?
    let scores = [9, 12, 7];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  28. 28.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Meera", "Aman", "Zoya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Kabir (c) Hi, Aman (d) Hi, Arjun
  29. 29.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Arjun", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Kabir (c) Hi, Riya
  30. 30.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Kabir", "Arjun", "Zoya", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Riya (c) Hi, Aman (d) Hi, Kabir
  31. 31.🔁 What number does this code show?
    let runs = [56, 16, 19, 34];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  32. 32.🔁 What number does this code show?
    let steps = [7, 13, 12];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  33. 33.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Arjun", "Zoya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Aman (c) Hi, Kabir (d) Hi, Riya
  34. 34.🔁 What number does this code show?
    let steps = [14, 13, 4];
    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 steps = [19, 13, 9, 4, 6];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  36. 36.🔁 What number does this code show?
    let scores = [8, 3, 14, 13, 8];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  37. 37.🔁 What number does this code show?
    let steps = [2, 11, 18];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  38. 38.🔁 What number does this code show?
    let marks = [10, 82, 27, 87, 29];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  39. 39.🔁 What number does this code show?
    let runs = [5, 17, 3, 12];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  40. 40.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Zoya", "Riya", "Aman", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Zoya (c) Hi, Riya (d) Hi, Kabir

Answer key

  1. 1
  2. 18
  3. 0
  4. 5
  5. 18
  6. 54
  7. Hi, Riya
  8. 18
  9. 20
  10. Hi, Zoya
  11. repeats code
  12. Hi, Meera
  13. less code to write
  14. 7
  15. 2
  16. 13
  17. Hi, Arjun
  18. Hi, Zoya
  19. 2
  20. 0
  21. how many items it has
  22. 12
  23. Hi, Riya
  24. 42
  25. 16
  26. 41
  27. 12
  28. Hi, Arjun
  29. Hi, Kabir
  30. Hi, Riya
  31. 0
  32. 13
  33. Hi, Aman
  34. 31
  35. 19
  36. 14
  37. 31
  38. 2
  39. 17
  40. Hi, Kabir

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