Answer:
I got B too so I sure could be right answer but if it's not then I so sorry. B. 6
 
        
                    
             
        
        
        
Answer: The p(success) = 0.6
Your question is a little unclear, but I believe you are asking about the probability that at least one of the trials in the experiment were successful.
If that is the case, you simply have to add the probability of 1 success with the probability of 2 successes.
That is 0.48 +  0.16 = 0.64
Rounding our answer to one decimal place gives us 0.6.
        
                    
             
        
        
        
Let V, be the rate in still water and let C = rate river current
If the boat is going :
upstream, its rate is V-C and if going 
downstream, its rate is V+C,
But V = 5C, then
Upstream Rate: 5C - C = 4 C
Downstream rate: 5C+C = 6C
Time = distance/Rate,  (or time = distance/speed) , then:
Upstream time 12/4C and
Downstream time: 12/.6C
Upstream time +downstream time:= 2h30 ' then:
12/4C + 12/.6C = 2.5 hours
3/C + 2/C = 5/2 (2.5 h = 5/2)
Reduce to same denominator :
 5C = 10 and Rate of the current = 2 mi/h
        
             
        
        
        
Answer:
No, they will need an additional £34 to stay the planned 10 nights.  
Step-by-step explanation:
Attached screenshot of a spreadsheet.
The cost for 10 nights for the 2 people is £100.
The tent site rental (over 10m^2) for 10 nights is £150.
Savings for the two over the 9 weeks is £216.
They will need an additional £34 to camp as planned.  
I suggest fibbing about the extra 0.5m^2 needed for the tent site.  That will reduce the bill by £30, so they are only £4 short.  Time to make a couple of friends.