360
400 - 40 = 360
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Answer:
the answer is A
Step-by-step explanation:
Answer:
Step-by-step explanation:
Given : A new catalyst is being investigated for use in the production of a plastic chemical. Ten batches of the chemical are produced. The mean yield of the 10 batches is 72.5% and the standard deviation is 5.8%. Assume the yields are independent and approximately normally distributed.
To find : A 99% confidence interval for the mean yield when the new catalyst is used ?
Solution :
Let X be the yield of the batches.
We have given, n=10 ,
, s=5.8%
Since the size of the sample is small.
We will use the student's t statistic to construct a 995 confidence interval.

From the t-table with 9 degree of freedom for 


The 99% confidence interval is given by,




Step-by-step explanation:
x = number of novels
y = number of dictionaries
x = 8y
88x + 208y = 13680
now, using the identity of the first equation in the second equation gives us
88(8y) + 208y = 13680
704y + 208y = 13680
912y = 13680
y = 13680/912 = 15
x = 8y = 8×15 = 120
so, there were 120 novels and 15 dictionaries sold.