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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 248 · 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.🔁 Why use a loop to show 100 messages? (a) less code to write (b) it is slower (c) it hides them (d) it uses more lines
  2. 2.🔁 What number does this code show?
    let runs = [14, 2, 20, 13];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  3. 3.🔁 What number does this code show?
    let scores = [14, 4, 7];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  4. 4.🔁 What number does this code show?
    let runs = [66, 13, 25, 99, 38];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  5. 5.🔁 What number does this code show?
    let steps = [6, 19, 4, 14, 11];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  6. 6.🔁 What number does this code show?
    let marks = [22, 79, 42, 80];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  7. 7.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Zoya", "Kabir", "Meera", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Zoya (c) Hi, Arjun (d) Hi, Aman
  8. 8.🔁 What number does this code show?
    let scores = [88, 32, 72, 45, 77];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  9. 9.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Zoya", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Meera (c) Hi, Riya
  10. 10.🔁 What number does this code show?
    let runs = [14, 10, 14, 6];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  11. 11.🔁 list.length tells you ___. (a) how many items it has (b) the last item (c) the biggest item (d) the first item
  12. 12.🔁 What number does this code show?
    let runs = [4, 15, 19, 14, 6];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  13. 13.🔁 What number does this code show?
    let steps = [85, 74, 72, 48, 99];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  14. 14.🔁 What number does this code show?
    let steps = [1, 11, 9, 14];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  15. 15.🔁 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, Aman (b) Hi, Kabir (c) Hi, Arjun
  16. 16.🔁 What number does this code show?
    let marks = [19, 14, 8, 8];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  17. 17.🔁 A loop over a list of 5 items runs its body how many times? (a) 4 (b) 5 (c) 1 (d) 6
  18. 18.🔁 What number does this code show?
    let steps = [7, 10, 15, 4];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  19. 19.🔁 What does a loop do? (a) deletes code (b) saves photos (c) repeats code (d) draws icons
  20. 20.🔁 What number does this code show?
    let steps = [5, 20, 2, 19];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  21. 21.🔁 What number does this code show?
    let runs = [20, 8, 20];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  22. 22.🔁 What number does this code show?
    let marks = [12, 8, 11, 10, 2];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  23. 23.🔁 What number does this code show?
    let marks = [11, 16, 19, 7];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  24. 24.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Meera", "Riya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Meera (c) Hi, Arjun (d) Hi, Zoya
  25. 25.🔁 What number does this code show?
    let steps = [79, 77, 36];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  26. 26.🔁 What number does this code show?
    let runs = [2, 5, 20, 7, 18];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  27. 27.🔁 What number does this code show?
    let steps = [9, 11, 17, 13];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  28. 28.🔁 What number does this code show?
    let runs = [90, 71, 33, 89];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  29. 29.🔁 What number does this code show?
    let runs = [20, 4, 4];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  30. 30.🔁 What number does this code show?
    let steps = [16, 6, 20];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  31. 31.🔁 What number does this code show?
    let runs = [89, 90, 17];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  32. 32.🔁 What number does this code show?
    let runs = [15, 1, 18];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  33. 33.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Zoya (c) Hi, Riya
  34. 34.🔁 What number does this code show?
    let steps = [9, 6, 2, 10];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  35. 35.🔁 What number does this code show?
    let scores = [19, 18, 16, 13, 1];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  36. 36.🔁 What number does this code show?
    let scores = [76, 31, 64, 48, 44];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  37. 37.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Arjun", "Aman", "Riya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Aman (c) Hi, Zoya (d) Hi, Kabir
  38. 38.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Zoya", "Riya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Aman (c) Hi, Riya (d) Hi, Zoya
  39. 39.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Zoya (c) Hi, Riya
  40. 40.🔁 What number does this code show?
    let runs = [5, 2, 3, 1, 17];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);

Answer key

  1. less code to write
  2. 20
  3. 14
  4. 2
  5. 19
  6. 2
  7. Hi, Arjun
  8. 4
  9. Hi, Riya
  10. 44
  11. how many items it has
  12. 58
  13. 4
  14. 35
  15. Hi, Kabir
  16. 49
  17. 5
  18. 36
  19. repeats code
  20. 20
  21. 20
  22. 43
  23. 53
  24. Hi, Arjun
  25. 2
  26. 52
  27. 50
  28. 3
  29. 20
  30. 42
  31. 2
  32. 18
  33. Hi, Kabir
  34. 10
  35. 67
  36. 2
  37. Hi, Kabir
  38. Hi, Aman
  39. Hi, Zoya
  40. 28

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