Answer:
c
Step-by-step explanation:
 
        
             
        
        
        
95% C.I. = 0.62 + or - 1.96 * sqrt[0.62(1 - 0.62)/34,271] = 0.62 + or - sqrt(6.875 x 10^-6) = 0.62 + or - 0.002622 = 0.62 - 0.002622 to 0.62 + 0.002622 = 0.6174 to 0.6226 = 61.74% to 62.26%.
        
             
        
        
        
Answer:
46 mph and 61 mph
Step-by-step explanation:
Distance=speed*time
Let speed of one bus be x and another x+15
After 3 hours
First bus would have traveled 3x while second bus 3(x+15)=3x+45
Total distance= 3x+3x+45=6x+45
6x+45=321
6x=321-45=276
x=276/6=46 mph
x+15=46+15=61 mph
 
        
             
        
        
        
Step-by-step answer:
We are looking at the coefficient of the 22nd term of (x+y)^25.
Following the sequence, first term is x^0y^25, second term is x^1y^24, third term is x^2y^23...and so on,  22nd term is x^21y^4.
The twenty-second term of (x+y)^25 is given by the binomial theorem as
 ( 25!/(21!4!) ) x^21*y^4
=25*24*23*22/4! x^21y^4
= 12650 x^21 y^4
The coefficient required is therefore 12650, for a binomial with unit valued coefficients.
For other binomials, substitute the values for x and y and expand accordingly.
Question would have been more clearly stated if the actual binomial was given, as commented above.
 
        
             
        
        
        
10C6 = 10!/(6!*(10-6)!) = 10*9*8*7/(4*3*2*1) = 210
There are 210 ways to choose 6 from a group of 10.