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App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 172 · 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) it hides them (b) less code to write (c) it uses more lines (d) it is slower
  2. 2.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Kabir", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Zoya (c) Hi, Kabir
  3. 3.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Aman", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Riya (c) Hi, Kabir
  4. 4.🔁 What is the LAST line this code shows?
    let names = ["Meera", "Zoya", "Arjun", "Kabir", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Zoya (c) Hi, Meera (d) Hi, Riya
  5. 5.🔁 What number does this code show?
    let steps = [13, 3, 11, 16];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  6. 6.🔁 In for (let i = 0; i < 3; i++), which values does i take? (a) 1, 2, 3 (b) 0, 1, 2, 3 (c) 0, 1, 2 (d) 3
  7. 7.🔁 What number does this code show?
    let runs = [8, 17, 1];
    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 marks = [17, 5, 20, 9, 4];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  9. 9.🔁 A loop over a list of 5 items runs its body how many times? (a) 1 (b) 6 (c) 4 (d) 5
  10. 10.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Zoya", "Arjun", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Zoya (c) Hi, Riya (d) Hi, Arjun
  11. 11.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Aman", "Meera", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Zoya (c) Hi, Kabir (d) Hi, Meera
  12. 12.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Arjun", "Aman", "Zoya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Kabir (b) Hi, Aman (c) Hi, Meera (d) Hi, Arjun
  13. 13.🔁 What number does this code show?
    let runs = [17, 74, 35];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  14. 14.🔁 What number does this code show?
    let scores = [24, 78, 91];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  15. 15.🔁 list.length tells you ___. (a) the last item (b) the first item (c) the biggest item (d) how many items it has
  16. 16.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Arjun", "Zoya", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Meera (c) Hi, Zoya (d) Hi, Kabir
  17. 17.🔁 What number does this code show?
    let runs = [79, 20, 97, 89];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  18. 18.🔁 What number does this code show?
    let steps = [20, 10, 18];
    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 scores = [68, 32, 93, 97, 11];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
  20. 20.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Arjun", "Riya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Riya (b) Hi, Arjun (c) Hi, Kabir
  21. 21.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Riya", "Arjun", "Meera", "Kabir"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Arjun (b) Hi, Riya (c) Hi, Kabir (d) Hi, Zoya
  22. 22.🔁 What number does this code show?
    let runs = [16, 5, 3, 7, 7];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  23. 23.🔁 What number does this code show?
    let marks = [90, 49, 14, 95];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  24. 24.🔁 What does a loop do? (a) saves photos (b) draws icons (c) repeats code (d) deletes code
  25. 25.🔁 What number does this code show?
    let scores = [11, 68, 87];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
  26. 26.🔁 What is the LAST line this code shows?
    let names = ["Aman", "Riya", "Kabir", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    }     (a) Hi, Aman (b) Hi, Riya (c) Hi, Kabir (d) Hi, Meera
  27. 27.🔁 What number does this code show?
    let scores = [3, 14, 13, 12, 10];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
  28. 28.🔁 What number does this code show?
    let marks = [2, 7, 13];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
  29. 29.🔁 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, Riya (b) Hi, Zoya (c) Hi, Kabir
  30. 30.🔁 What number does this code show?
    let runs = [10, 18, 10];
    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 steps = [12, 2, 19, 2, 18];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
  32. 32.🔁 What number does this code show?
    let runs = [14, 19, 9, 12, 14];
    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 = [4, 19, 7];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
  34. 34.🔁 What number does this code show?
    let marks = [17, 13, 18];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
  35. 35.🔁 What number does this code show?
    let scores = [95, 61, 18];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
  36. 36.🔁 What number does this code show?
    let scores = [34, 59, 90, 10, 93];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
  37. 37.🔁 What number does this code show?
    let runs = [11, 9, 12, 16];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  38. 38.🔁 What number does this code show?
    let steps = [14, 9, 1, 18, 1];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
  39. 39.🔁 What number does this code show?
    let runs = [11, 18, 20, 11];
    let best = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] > best) {
        best = runs[i];
      }
    }
    show(best);
  40. 40.🔁 What number does this code show?
    let steps = [30, 81, 44, 10, 52];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);

Answer key

  1. less code to write
  2. Hi, Arjun
  3. Hi, Riya
  4. Hi, Riya
  5. 43
  6. 0, 1, 2
  7. 26
  8. 20
  9. 5
  10. Hi, Riya
  11. Hi, Kabir
  12. Hi, Meera
  13. 1
  14. 2
  15. how many items it has
  16. Hi, Meera
  17. 3
  18. 20
  19. 3
  20. Hi, Riya
  21. Hi, Kabir
  22. 38
  23. 2
  24. repeats code
  25. 1
  26. Hi, Meera
  27. 52
  28. 13
  29. Hi, Kabir
  30. 38
  31. 19
  32. 19
  33. 30
  34. 48
  35. 2
  36. 3
  37. 16
  38. 43
  39. 20
  40. 2

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