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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 238 · 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 is the LAST line this code shows?
    let names = ["Aman", "Riya", "Kabir", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Arjun (c) Hi, Aman (d) Hi, Kabir
  2. 2.🔁 What number does this code show?
    let runs = [13, 6, 2];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  3. 3.🔁 A loop over a list of 5 items runs its body how many times? (a) 5 (b) 4 (c) 6 (d) 1
  4. 4.🔁 What number does this code show?
    let steps = [9, 2, 2, 5, 8];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  5. 5.🔁 What does a loop do? (a) repeats code (b) deletes code (c) draws icons (d) saves photos
  6. 6.🔁 What number does this code show?
    let runs = [34, 55, 12, 44];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  7. 7.🔁 What number does this code show?
    let runs = [12, 19, 13];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  8. 8.🔁 What number does this code show?
    let scores = [9, 5, 12];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  9. 9.🔁 What number does this code show?
    let scores = [15, 19, 2, 15];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  10. 10.🔁 What number does this code show?
    let runs = [11, 19, 15, 7];
    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 = ["Zoya", "Riya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Zoya (b) Hi, Riya (c) Hi, Aman
  12. 12.🔁 What number does this code show?
    let steps = [18, 17, 6];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  13. 13.🔁 What number does this code show?
    let steps = [1, 17, 13];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  14. 14.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 0, 1, 2, 3 (b) 1, 2, 3 (c) 3 (d) 0, 1, 2
  15. 15.🔁 What number does this code show?
    let scores = [25, 54, 27, 32];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  16. 16.🔁 What number does this code show?
    let steps = [15, 1, 17, 9, 5];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  17. 17.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Arjun", "Riya", "Aman", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Zoya (c) Hi, Arjun (d) Hi, Meera
  18. 18.🔁 What number does this code show?
    let scores = [11, 6, 17, 12];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  19. 19.🔁 What number does this code show?
    let scores = [83, 68, 50];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  20. 20.🔁 What number does this code show?
    let marks = [1, 3, 5, 12, 4];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  21. 21.🔁 What number does this code show?
    let runs = [17, 2, 9, 14];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  22. 22.🔁 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
  23. 23.🔁 What number does this code show?
    let runs = [11, 14, 8, 3, 1];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  24. 24.🔁 What number does this code show?
    let steps = [30, 99, 98, 19, 50];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  25. 25.🔁 What number does this code show?
    let scores = [73, 11, 99];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  26. 26.🔁 What number does this code show?
    let steps = [8, 15, 3];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  27. 27.🔁 What number does this code show?
    let runs = [6, 8, 10, 15, 16];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  28. 28.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Riya", "Zoya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Zoya (c) Hi, Aman (d) Hi, Meera
  29. 29.🔁 What number does this code show?
    let marks = [4, 12, 11];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  30. 30.🔁 What number does this code show?
    let runs = [6, 5, 3];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  31. 31.🔁 What number does this code show?
    let marks = [2, 2, 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 = [6, 17, 8];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  33. 33.🔁 What number does this code show?
    let runs = [64, 88, 30, 69];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  34. 34.🔁 What number does this code show?
    let steps = [98, 95, 19];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  35. 35.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Arjun", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Arjun (c) Hi, Riya
  36. 36.🔁 list.length tells you ___. (a) the first item (b) how many items it has (c) the biggest item (d) the last item
  37. 37.🔁 What number does this code show?
    let runs = [36, 17, 56, 14];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  38. 38.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Meera", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Meera (c) Hi, Arjun
  39. 39.🔁 What number does this code show?
    let steps = [12, 30, 77];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  40. 40.🔁 What number does this code show?
    let runs = [18, 7, 7];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);

Answer key

  1. Hi, Arjun
  2. 21
  3. 5
  4. 9
  5. repeats code
  6. 1
  7. 44
  8. 12
  9. 19
  10. 52
  11. Hi, Aman
  12. 18
  13. 17
  14. 0, 1, 2
  15. 1
  16. 47
  17. Hi, Meera
  18. 17
  19. 1
  20. 25
  21. 42
  22. less code to write
  23. 14
  24. 3
  25. 2
  26. 15
  27. 16
  28. Hi, Aman
  29. 27
  30. 14
  31. 4
  32. 17
  33. 1
  34. 2
  35. Hi, Riya
  36. how many items it has
  37. 0
  38. Hi, Kabir
  39. 1
  40. 32

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