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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 287 · 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 = [12, 5, 1, 5];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  2. 2.🔁 What does a loop do? (a) repeats code (b) draws icons (c) deletes code (d) saves photos
  3. 3.🔁 What number does this code show?
    let scores = [22, 97, 87];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  4. 4.🔁 What number does this code show?
    let scores = [9, 8, 8];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  5. 5.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Kabir", "Riya", "Meera", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Kabir (c) Hi, Riya (d) Hi, Zoya
  6. 6.🔁 What number does this code show?
    let steps = [10, 18, 2];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  7. 7.🔁 What number does this code show?
    let runs = [5, 10, 9, 13];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  8. 8.🔁 What number does this code show?
    let scores = [1, 2, 15];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  9. 9.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Zoya (c) Hi, Kabir (d) Hi, Riya
  10. 10.🔁 What number does this code show?
    let marks = [8, 15, 15, 1, 13];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  11. 11.🔁 What number does this code show?
    let steps = [10, 15, 14, 3, 4];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  12. 12.🔁 list.length tells you ___. (a) the biggest item (b) how many items it has (c) the first item (d) the last item
  13. 13.🔁 What number does this code show?
    let scores = [38, 53, 70, 39, 97];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  14. 14.🔁 What number does this code show?
    let marks = [41, 34, 58, 85, 96];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  15. 15.🔁 What number does this code show?
    let scores = [4, 20, 15, 8];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  16. 16.🔁 What number does this code show?
    let runs = [8, 18, 2];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  17. 17.🔁 What number does this code show?
    let runs = [15, 12, 11, 10];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  18. 18.🔁 What number does this code show?
    let steps = [15, 14, 10];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  19. 19.🔁 What number does this code show?
    let marks = [1, 9, 2, 1, 20];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  20. 20.🔁 What number does this code show?
    let scores = [18, 2, 6, 16];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  21. 21.🔁 What number does this code show?
    let runs = [11, 16, 4, 6, 7];
    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 steps = [16, 14, 7];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  23. 23.🔁 A loop over a list of 5 items runs its body how many times? (a) 1 (b) 6 (c) 4 (d) 5
  24. 24.🔁 What number does this code show?
    let scores = [11, 99, 23, 44, 24];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  25. 25.🔁 What number does this code show?
    let marks = [6, 17, 13, 6, 5];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  26. 26.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Kabir (c) Hi, Arjun
  27. 27.🔁 Why use a loop to show 100 messages? (a) it is slower (b) less code to write (c) it uses more lines (d) it hides them
  28. 28.🔁 What number does this code show?
    let marks = [6, 15, 18, 9];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  29. 29.🔁 What number does this code show?
    let steps = [5, 8, 8, 2];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  30. 30.🔁 What number does this code show?
    let runs = [2, 2, 3, 11, 1];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  31. 31.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Arjun", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Meera (c) Hi, Riya
  32. 32.🔁 What number does this code show?
    let steps = [14, 15, 11];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  33. 33.🔁 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
  34. 34.🔁 What number does this code show?
    let marks = [96, 61, 78, 28, 34];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  35. 35.🔁 What number does this code show?
    let steps = [20, 15, 19];
    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, 72, 42];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  37. 37.🔁 What number does this code show?
    let marks = [14, 19, 17, 14];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  38. 38.🔁 What number does this code show?
    let marks = [46, 48, 75, 99];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  39. 39.🔁 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, Kabir (b) Hi, Riya (c) Hi, Aman (d) Hi, Zoya
  40. 40.🔁 What number does this code show?
    let runs = [73, 91, 67];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);

Answer key

  1. 12
  2. repeats code
  3. 2
  4. 9
  5. Hi, Aman
  6. 18
  7. 13
  8. 15
  9. Hi, Kabir
  10. 15
  11. 15
  12. how many items it has
  13. 2
  14. 4
  15. 20
  16. 28
  17. 15
  18. 15
  19. 20
  20. 18
  21. 16
  22. 37
  23. 5
  24. 2
  25. 17
  26. Hi, Arjun
  27. less code to write
  28. 48
  29. 23
  30. 19
  31. Hi, Meera
  32. 40
  33. 0, 1, 2
  34. 3
  35. 20
  36. 2
  37. 64
  38. 4
  39. Hi, Zoya
  40. 3

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