Answer:
its 55
Step-by-step explanation:
Answer:
The top 20% of the students will score at least 2.1 points above the mean.
Step-by-step explanation:
When the distribution is normal, we use the z-score formula.
In a set with mean
and standard deviation
, the zscore of a measure X is given by:

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
The mean of a certain test is 14 and the standard deviation is 2.5.
This means that 
The top 20% of the students will score how many points above the mean
Their score is the 100 - 20 = 80th percentile, which is X when Z has a pvalue of 0.8. So X when Z = 0.84.
Their score is:




16.1 - 14 = 2.1
The top 20% of the students will score at least 2.1 points above the mean.
Answer: a) 15625, b) 0.2, c) 625, d) 0.008.
Step-by-step explanation:
Since we have given that
a) 
As we know that

So, it becomes,

(b) 
So, it becomes,

(c) 
As we know that

So, it becomes,

(d) 

Hence, a) 15625, b) 0.2, c) 625, d) 0.008.
Answer:
C. 63.4
Step-by-step explanation: