Answer:
225
Step-by-step explanation:
Using the basic components of summation ∑
∑n = n(n + 1) and ∑1 = n
Thus
∑ (2n - 1) ← for n = 1 to 15
= ∑2n - ∑1
= 2∑n - ∑1
= 2 ( n(n + 1)) - n
= n(n + 1) - n ← Evaluate for n = 15 ( the upper value )
= 15 × 16 - 15
= 240 - 15
= 225
Answer:
Step-by-step explanation:
Given that Prof Liu gave the same quiz to the students in her morning class and in her afternoon class. the average score for the two classes combined was 84.
(1) The average score for the students in the morning class was 80
(2) the average score for the students in the afternoon class was 86
Let m be the no of students in I class and n in II class
Total of I class = 80m and
Total of II class = 86n
Total of both classes = 80m +86n
Average =
m cannot be equal to n because in that case average would have been 83
If m >n, then say n =m+a
then average =
Because 86 is more times added, average score would decrease hence we would not get 84.
So I class is getting less score of 80 to get a score average of more than 83 (the average) the class II should have more students.