Let number of books by astrid's = x
Out of x , 84% are fiction.
So, Number of non fictional books = x - 
= 
→Ratio of number of books to fictional books
⇒[Dividing numerator and denominator by 4.]
→Out of 25 books by astrid 21 are fictional.
→ Number of fictional books by astrid = 
The answer for this question is 1,100
Answer:
x=-75
Step-by-step explanation:
Answer:
(25.732,30.868)
Step-by-step explanation:
Given that in a random sample of 42 people, the mean body mass index (BMI) was 28.3 and the standard deviation was 6.09.
Since only sample std deviation is known we can use only t distribution
Std error = 

t critical for 99% two tailed 
Margin of error
Confidence interval lower bound = 
Upper bound = 