Answer:
2,436 students
Step-by-step explanation:
At a 90% confidence level, the z-score is 1.645 and the confidence interval is given by:
Where s is the standard deviation, and n is the sample size.
If they want the length of their confidence interval to be no greater than 0.2, it must be no further than 0.1 from the mean 'X':
Rounding up to the next whole number, the sample size should be 2,436 students.
Answer:
The common difference of the progression is 3.
Step-by-step explanation:
Given:
First term of the AP = (a) = -8
Ratio of 7th and 9th term = 5:8
So,
General term of an AP, Tn= a+(n-1)d
Where 'd' is the common difference.
equation...(i)
equation...(ii)
According to the question.
⇒ ...cross-multiplying the terms.
⇒
⇒
⇒ ...subtracting 40d and adding 64 both sides.
⇒
⇒ ...dividing both sides with 3.
So the common difference of the progression is 'd' = 3.