App Dev Worksheet: Loops over Lists

App development lesson 19: Loops over lists · Set 770 · 40 questions

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.

1. 1.🔁 What number does this code show?
   let scores = [14, 97, 76, 85, 48];
   let count = 0;
   for (let i = 0; i < scores.length; i++) {
     if (scores[i] >= 40) {
       count = count + 1;
     }
   }
   show(count);
2. 2.🔁 What is the LAST line this code shows?
   let names = ["Riya", "Meera", "Aman"];
   for (let i = 0; i < names.length; i++) {
     show("Hi, " + names[i]);
   } (a) Hi, Meera (b) Hi, Aman (c) Hi, Riya
3. 3.🔁 A loop over a list of 5 items runs its body how many times? (a) 1 (b) 4 (c) 6 (d) 5
4. 4.🔁 What number does this code show?
   let scores = [58, 47, 40];
   let count = 0;
   for (let i = 0; i < scores.length; i++) {
     if (scores[i] >= 40) {
       count = count + 1;
     }
   }
   show(count);
5. 5.🔁 What number does this code show?
   let marks = [18, 1, 11, 11, 17];
   let total = 0;
   for (let i = 0; i < marks.length; i++) {
     total = total + marks[i];
   }
   show(total);
6. 6.🔁 What number does this code show?
   let marks = [10, 1, 2];
   let best = 0;
   for (let i = 0; i < marks.length; i++) {
     if (marks[i] > best) {
       best = marks[i];
     }
   }
   show(best);
7. 7.🔁 What number does this code show?
   let steps = [3, 9, 2, 1];
   let best = 0;
   for (let i = 0; i < steps.length; i++) {
     if (steps[i] > best) {
       best = steps[i];
     }
   }
   show(best);
8. 8.🔁 What number does this code show?
   let marks = [17, 49, 69];
   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 runs = [12, 15, 18];
   let best = 0;
   for (let i = 0; i < runs.length; i++) {
     if (runs[i] > best) {
       best = runs[i];
     }
   }
   show(best);
10. 10.🔁 Why use a loop to show 100 messages? (a) it uses more lines (b) it is slower (c) it hides them (d) less code to write
11. 11.🔁 What number does this code show?
    let scores = [13, 20, 2, 2];
    let total = 0;
    for (let i = 0; i < scores.length; i++) {
      total = total + scores[i];
    }
    show(total);
12. 12.🔁 What number does this code show?
    let scores = [52, 54, 99, 30];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
13. 13.🔁 What number does this code show?
    let marks = [19, 8, 13, 8];
    let total = 0;
    for (let i = 0; i < marks.length; i++) {
      total = total + marks[i];
    }
    show(total);
14. 14.🔁 What number does this code show?
    let steps = [29, 86, 33, 79, 66];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
15. 15.🔁 What number does this code show?
    let scores = [17, 4, 6, 6, 5];
    let best = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] > best) {
        best = scores[i];
      }
    }
    show(best);
16. 16.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Meera", "Kabir", "Zoya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Meera (b) Hi, Aman (c) Hi, Riya (d) Hi, Kabir
17. 17.🔁 What number does this code show?
    let marks = [10, 3, 9, 7, 11];
    let best = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] > best) {
        best = marks[i];
      }
    }
    show(best);
18. 18.🔁 What number does this code show?
    let runs = [17, 5, 9, 12, 3];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
19. 19.🔁 What number does this code show?
    let steps = [13, 11, 3, 6];
    let best = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] > best) {
        best = steps[i];
      }
    }
    show(best);
20. 20.🔁 What number does this code show?
    let marks = [12, 15, 5, 16];
    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 = [23, 27, 88];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);
22. 22.🔁 list.length tells you ___. (a) the first item (b) the biggest item (c) how many items it has (d) the last item
23. 23.🔁 What number does this code show?
    let runs = [97, 10, 78];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
24. 24.🔁 What number does this code show?
    let runs = [93, 80, 41, 36];
    let count = 0;
    for (let i = 0; i < runs.length; i++) {
      if (runs[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
25. 25.🔁 What number does this code show?
    let steps = [42, 87, 69];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 40) {
        count = count + 1;
      }
    }
    show(count);
26. 26.🔁 What is the LAST line this code shows?
    let names = ["Riya", "Zoya", "Aman", "Meera"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Zoya (b) Hi, Riya (c) Hi, Aman (d) Hi, Meera
27. 27.🔁 What number does this code show?
    let scores = [4, 20, 19];
    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 = [86, 23, 57];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
29. 29.🔁 What number does this code show?
    let scores = [33, 38, 45, 23, 21];
    let count = 0;
    for (let i = 0; i < scores.length; i++) {
      if (scores[i] >= 60) {
        count = count + 1;
      }
    }
    show(count);
30. 30.🔁 What number does this code show?
    let steps = [15, 9, 8];
    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 steps = [5, 10, 8];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
32. 32.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Arjun", "Kabir", "Riya", "Aman"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Arjun (c) Hi, Zoya (d) Hi, Aman
33. 33.🔁 What number does this code show?
    let steps = [88, 53, 31, 86, 98];
    let count = 0;
    for (let i = 0; i < steps.length; i++) {
      if (steps[i] >= 70) {
        count = count + 1;
      }
    }
    show(count);
34. 34.🔁 What number does this code show?
    let runs = [3, 12, 9];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
35. 35.🔁 What number does this code show?
    let runs = [12, 20, 14, 13, 16];
    let total = 0;
    for (let i = 0; i < runs.length; i++) {
      total = total + runs[i];
    }
    show(total);
36. 36.🔁 What number does this code show?
    let steps = [19, 9, 11, 9, 2];
    let total = 0;
    for (let i = 0; i < steps.length; i++) {
      total = total + steps[i];
    }
    show(total);
37. 37.🔁 What is the LAST line this code shows?
    let names = ["Zoya", "Meera", "Arjun"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Arjun (b) Hi, Meera (c) Hi, Zoya
38. 38.🔁 What is the LAST line this code shows?
    let names = ["Kabir", "Riya", "Zoya"];
    for (let i = 0; i < names.length; i++) {
      show("Hi, " + names[i]);
    } (a) Hi, Kabir (b) Hi, Riya (c) Hi, Zoya
39. 39.🔁 What number does this code show?
    let runs = [20, 19, 3, 10];
    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 marks = [36, 15, 82, 14];
    let count = 0;
    for (let i = 0; i < marks.length; i++) {
      if (marks[i] >= 50) {
        count = count + 1;
      }
    }
    show(count);

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