First we need to know how much each pen costs.  So we take 11.77 and divide it by 11.  That gives us 1.07 per pen.  So answer choice A has 4 pens for 4.44, so we need to multiply 1.07 x 4.  That gives you 4.28, so we know that isn't the correct answer.  For option B, we need to multiply 1.07 x 5.  That is 5.35, so that also can't be the answer.  For C, we need to do 1.07 x 6, and that gives us 6.42.  So we know the correct answer is option C.
        
                    
             
        
        
        
Answer:
⇒  The given quadratic equation is x2−kx+9=0, comparing it with ax2+bx+c=0
∴  We get, a=1b=−k,c=9
⇒  It is given that roots are real and distinct.
∴  b2−4ac>0
⇒  (−k)2−4(1)(9)>0
⇒  k2−36>0
⇒  k2>36
⇒  k>6 or k<−6
∴  We can see values of k given in question are correct.
 
        
             
        
        
        
Answer:
2.5 miles
Step-by-step explanation:
 
        
             
        
        
        
Answer:
68.26% probability that a randomly selected full-term pregnancy baby's birth weight is between 6.4 and 8.6 pounds
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:

What is the probability that a randomly selected full-term pregnancy baby's birth weight is between 6.4 and 8.6 pounds
This is the pvalue of Z when X = 8.6 subtracted by the pvalue of Z when X = 6.4. So
X = 8.6



 has a pvalue of 0.8413
 has a pvalue of 0.8413
X = 6.4



 has a pvalue of 0.1587
 has a pvalue of 0.1587
0.8413 - 0.1587 = 0.6826
68.26% probability that a randomly selected full-term pregnancy baby's birth weight is between 6.4 and 8.6 pounds