Answer:
a) 6.68th percentile
b) 617.5 points
Step-by-step explanation:
Problems of normally distributed samples are solved using the z-score formula.
In a set with mean  and standard deviation
 and standard deviation  , the zscore of a measure X is given by:
, 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.
In this problem, we have that:

a) A student who scored 400 on the Math SAT was at the ______ th percentile of the score distribution.



 has a pvalue of 0.0668
 has a pvalue of 0.0668
So this student is in the 6.68th percentile.
b) To be at the 75th percentile of the distribution, a student needed a score of about ______ points on the Math SAT.
He needs a score of X when Z has a pvalue of 0.75. So X when Z = 0.675.




 
        
             
        
        
        
Answer:
i think the answer is 25q - 5 / 4
 
        
             
        
        
        
Answer: k=9/4
Step-by-step explanation: We can do this by finding a number that adds up to 3 when multiplied by 2. The best way to do this is to use ((b^2)/4) which can usually find you the number for a perfect square based on b, which we have. So, 3^2 / 4 =9/4, meaning k=9/4. We can check:
>x^2 +3x +9/4
> (x+3/2)(x+3/2)
Perfect square.
 
        
             
        
        
        
Answer:
22.5 i thiink
Step-by-step explanation:
9,4,5.     12
18
o24
which means it is...
look at the answer
 
        
                    
             
        
        
        
The number of small tiles are needed is 300 tiles.
<h3>Number of tiles needed</h3>
Using area of rectangular formula
Area of the room = length(l) × breadth (b)
Area of the room=300 cm×180 cm
Area of the room=54,000 cm²
Number of tiles needed = Area of rectangular region / Area of one tile
Number of tiles needed=54,000/180
Number of tiles needed=300 tiles
Therefore the number of small tiles are needed is 300 tiles.
Learn more about number of tiles needed here:brainly.com/question/2136390
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