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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 219 · 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 = [75, 41, 43, 14];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  2. 2.🔁 What number does this code show?
    let scores = [1, 16, 1, 7];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  3. 3.🔁 What number does this code show?
    let runs = [18, 16, 14, 13];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  4. 4.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 1, 2, 3 (b) 0, 1, 2, 3 (c) 3 (d) 0, 1, 2
  5. 5.🔁 What number does this code show?
    let scores = [42, 76, 61];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  6. 6.🔁 What number does this code show?
    let steps = [5, 3, 13];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  7. 7.🔁 What number does this code show?
    let runs = [5, 8, 3, 7];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  8. 8.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Riya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Riya (c) Hi, Aman
  9. 9.🔁 What number does this code show?
    let runs = [5, 18, 7];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  10. 10.🔁 What number does this code show?
    let runs = [4, 7, 2, 12, 8];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  11. 11.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Arjun", "Kabir", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Aman (c) Hi, Kabir (d) Hi, Arjun
  12. 12.🔁 A loop over a list of 5 items runs its body how many times? (a) 4 (b) 5 (c) 1 (d) 6
  13. 13.🔁 What number does this code show?
    let runs = [16, 19, 8];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  14. 14.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Zoya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Riya (c) Hi, Zoya (d) Hi, Aman
  15. 15.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Kabir", "Arjun", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Zoya (c) Hi, Riya (d) Hi, Arjun
  16. 16.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Meera (c) Hi, Riya
  17. 17.🔁 list.length tells you ___. (a) how many items it has (b) the biggest item (c) the last item (d) the first item
  18. 18.🔁 What number does this code show?
    let steps = [16, 14, 20, 9];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  19. 19.🔁 What number does this code show?
    let scores = [10, 8, 7];
    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 steps = [3, 10, 16, 6, 12];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  21. 21.🔁 What number does this code show?
    let scores = [16, 76, 10, 45];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  22. 22.🔁 What number does this code show?
    let scores = [65, 32, 18, 76, 97];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  23. 23.🔁 What number does this code show?
    let runs = [10, 7, 16];
    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 = ["Kabir", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Kabir (c) Hi, Zoya
  25. 25.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Riya (c) Hi, Aman
  26. 26.🔁 What does a loop do? (a) deletes code (b) draws icons (c) saves photos (d) repeats code
  27. 27.🔁 Why use a loop to show 100 messages? (a) less code to write (b) it hides them (c) it uses more lines (d) it is slower
  28. 28.🔁 What number does this code show?
    let runs = [76, 73, 52, 51];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  29. 29.🔁 What number does this code show?
    let steps = [2, 9, 6, 6, 11];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  30. 30.🔁 What number does this code show?
    let marks = [19, 2, 15, 3, 3];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  31. 31.🔁 What number does this code show?
    let marks = [87, 30, 46, 40, 72];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  32. 32.🔁 What number does this code show?
    let marks = [8, 7, 16];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  33. 33.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Aman", "Kabir", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Arjun (c) Hi, Zoya (d) Hi, Aman
  34. 34.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Kabir", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Kabir (c) Hi, Riya
  35. 35.🔁 What number does this code show?
    let scores = [33, 61, 42, 11];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  36. 36.🔁 What number does this code show?
    let scores = [19, 12, 17, 17, 7];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  37. 37.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Meera", "Aman", "Zoya", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Riya (c) Hi, Meera (d) Hi, Arjun
  38. 38.🔁 What number does this code show?
    let scores = [64, 60, 70, 76];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  39. 39.🔁 What number does this code show?
    let marks = [22, 24, 64];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  40. 40.🔁 What number does this code show?
    let steps = [6, 10, 2];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);

Answer key

  1. 1
  2. 25
  3. 61
  4. 0, 1, 2
  5. 1
  6. 21
  7. 23
  8. Hi, Aman
  9. 18
  10. 33
  11. Hi, Zoya
  12. 5
  13. 19
  14. Hi, Aman
  15. Hi, Riya
  16. Hi, Meera
  17. how many items it has
  18. 59
  19. 10
  20. 47
  21. 1
  22. 3
  23. 16
  24. Hi, Zoya
  25. Hi, Aman
  26. repeats code
  27. less code to write
  28. 4
  29. 11
  30. 42
  31. 2
  32. 16
  33. Hi, Zoya
  34. Hi, Riya
  35. 1
  36. 72
  37. Hi, Riya
  38. 2
  39. 1
  40. 10

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