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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 318 · 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.🔁 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
  2. 2.🔁 What number does this code show?
    let steps = [3, 9, 20, 2];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  3. 3.🔁 What number does this code show?
    let marks = [12, 19, 4];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  4. 4.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Kabir", "Aman", "Meera", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Arjun (c) Hi, Kabir (d) Hi, Aman
  5. 5.🔁 A loop over a list of 5 items runs its body how many times? (a) 4 (b) 5 (c) 1 (d) 6
  6. 6.🔁 What number does this code show?
    let steps = [52, 70, 19];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  7. 7.🔁 What number does this code show?
    let steps = [12, 3, 5];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  8. 8.🔁 What number does this code show?
    let marks = [28, 15, 29];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  9. 9.🔁 What number does this code show?
    let marks = [2, 4, 13, 3, 7];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  10. 10.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Arjun", "Zoya", "Aman", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Kabir (c) Hi, Zoya (d) Hi, Meera
  11. 11.🔁 What number does this code show?
    let runs = [1, 5, 2, 9, 2];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  12. 12.🔁 What number does this code show?
    let marks = [10, 12, 13, 9];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  13. 13.🔁 What number does this code show?
    let scores = [70, 27, 99];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  14. 14.🔁 What number does this code show?
    let marks = [14, 12, 5, 8];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  15. 15.🔁 What does a loop do? (a) repeats code (b) draws icons (c) deletes code (d) saves photos
  16. 16.🔁 What number does this code show?
    let steps = [17, 17, 2, 3, 5];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  17. 17.🔁 What number does this code show?
    let scores = [9, 11, 14, 17, 9];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  18. 18.🔁 What number does this code show?
    let scores = [42, 14, 68, 20, 32];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  19. 19.🔁 What number does this code show?
    let steps = [2, 3, 7];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  20. 20.🔁 What number does this code show?
    let runs = [55, 55, 57, 34, 51];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  21. 21.🔁 What number does this code show?
    let runs = [14, 13, 17, 6];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  22. 22.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Kabir", "Meera", "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
  23. 23.🔁 list.length tells you ___. (a) the first item (b) the biggest item (c) the last item (d) how many items it has
  24. 24.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Arjun (c) Hi, Riya
  25. 25.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Zoya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Kabir (c) Hi, Meera
  26. 26.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Arjun", "Zoya", "Aman", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Zoya (c) Hi, Arjun (d) Hi, Riya
  27. 27.🔁 What number does this code show?
    let marks = [13, 13, 17, 10];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  28. 28.🔁 What number does this code show?
    let steps = [4, 20, 4, 12, 9];
    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 = [2, 16, 13, 1];
    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 marks = [19, 14, 14];
    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 = [2, 5, 5, 4];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  32. 32.🔁 What number does this code show?
    let runs = [60, 18, 42];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  33. 33.🔁 What number does this code show?
    let runs = [4, 4, 7];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  34. 34.🔁 Why use a loop to show 100 messages? (a) it hides them (b) less code to write (c) it is slower (d) it uses more lines
  35. 35.🔁 What number does this code show?
    let steps = [16, 7, 10, 1];
    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 runs = [21, 94, 52, 27];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  37. 37.🔁 What number does this code show?
    let marks = [4, 15, 9, 12, 18];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  38. 38.🔁 What number does this code show?
    let scores = [25, 77, 58, 32, 52];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  39. 39.🔁 What number does this code show?
    let marks = [14, 15, 11, 11, 2];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  40. 40.🔁 What number does this code show?
    let steps = [17, 12, 1];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);

Answer key

  1. 0, 1, 2
  2. 20
  3. 35
  4. Hi, Arjun
  5. 5
  6. 2
  7. 20
  8. 0
  9. 13
  10. Hi, Kabir
  11. 19
  12. 13
  13. 2
  14. 39
  15. repeats code
  16. 44
  17. 60
  18. 2
  19. 12
  20. 4
  21. 17
  22. Hi, Zoya
  23. how many items it has
  24. Hi, Arjun
  25. Hi, Meera
  26. Hi, Kabir
  27. 53
  28. 20
  29. 16
  30. 47
  31. 5
  32. 2
  33. 15
  34. less code to write
  35. 16
  36. 1
  37. 18
  38. 3
  39. 15
  40. 17

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