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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 553 · 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 marks = [20, 10, 15, 19, 8];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  2. 2.🔁 What number does this code show?
    let scores = [3, 5, 16];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  3. 3.🔁 What number does this code show?
    let marks = [49, 32, 50];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  4. 4.🔁 What number does this code show?
    let steps = [55, 60, 87, 80, 66];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  5. 5.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Aman", "Riya", "Kabir", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Zoya (c) Hi, Aman (d) Hi, Arjun
  6. 6.🔁 A loop over a list of 5 items runs its body how many times? (a) 4 (b) 5 (c) 1 (d) 6
  7. 7.🔁 What does a loop do? (a) draws icons (b) deletes code (c) saves photos (d) repeats code
  8. 8.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Aman", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Aman (c) Hi, Zoya
  9. 9.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Meera", "Riya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Riya (c) Hi, Arjun (d) Hi, Meera
  10. 10.🔁 What number does this code show?
    let steps = [17, 11, 19, 7, 17];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  11. 11.🔁 What number does this code show?
    let runs = [9, 1, 11, 14, 9];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  12. 12.🔁 What number does this code show?
    let scores = [3, 11, 3, 4, 3];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  13. 13.🔁 What is the LAST line this code shows?
    let names = ["Arjun", "Zoya", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Riya (c) Hi, Zoya
  14. 14.🔁 Why use a loop to show 100 messages? (a) it uses more lines (b) it hides them (c) it is slower (d) less code to write
  15. 15.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Meera", "Zoya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Meera (c) Hi, Aman (d) Hi, Riya
  16. 16.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Meera", "Zoya", "Arjun", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Riya (c) Hi, Meera (d) Hi, Zoya
  17. 17.🔁 What number does this code show?
    let scores = [55, 30, 42, 52];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  18. 18.🔁 What number does this code show?
    let steps = [2, 13, 5, 16, 10];
    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 marks = [39, 23, 14, 91];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  20. 20.🔁 What number does this code show?
    let runs = [1, 2, 20, 13];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  21. 21.🔁 What number does this code show?
    let steps = [15, 4, 8, 11, 5];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  22. 22.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Kabir", "Aman", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Meera (b) Hi, Aman (c) Hi, Riya (d) Hi, Kabir
  23. 23.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Zoya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Zoya (c) Hi, Arjun (d) Hi, Aman
  24. 24.🔁 What number does this code show?
    let steps = [12, 16, 14, 10];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  25. 25.🔁 What number does this code show?
    let runs = [2, 3, 6, 20, 8];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  26. 26.🔁 What number does this code show?
    let scores = [4, 3, 8, 10];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  27. 27.🔁 What number does this code show?
    let steps = [6, 18, 14];
    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 scores = [4, 20, 1, 1, 13];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  29. 29.🔁 What number does this code show?
    let marks = [63, 46, 42, 99, 25];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  30. 30.🔁 What number does this code show?
    let steps = [3, 16, 5, 1];
    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 scores = [99, 39, 25, 11];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  32. 32.🔁 What number does this code show?
    let runs = [5, 20, 7, 8, 16];
    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 marks = [58, 45, 61];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  34. 34.🔁 list.length tells you ___. (a) how many items it has (b) the first item (c) the last item (d) the biggest item
  35. 35.🔁 What number does this code show?
    let scores = [6, 19, 13, 10, 9];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  36. 36.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Zoya", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Kabir (c) Hi, Zoya
  37. 37.🔁 What number does this code show?
    let scores = [18, 3, 1, 16];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
  38. 38.🔁 What number does this code show?
    let runs = [28, 38, 40, 36];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  39. 39.🔁 What number does this code show?
    let steps = [22, 94, 14, 22];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  40. 40.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Arjun (c) Hi, Zoya

Answer key

  1. 72
  2. 16
  3. 0
  4. 5
  5. Hi, Arjun
  6. 5
  7. repeats code
  8. Hi, Zoya
  9. Hi, Arjun
  10. 71
  11. 14
  12. 11
  13. Hi, Riya
  14. less code to write
  15. Hi, Arjun
  16. Hi, Riya
  17. 3
  18. 46
  19. 1
  20. 20
  21. 15
  22. Hi, Riya
  23. Hi, Arjun
  24. 16
  25. 39
  26. 25
  27. 38
  28. 20
  29. 4
  30. 25
  31. 1
  32. 20
  33. 3
  34. how many items it has
  35. 57
  36. Hi, Kabir
  37. 18
  38. 0
  39. 1
  40. Hi, Arjun

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