1.  87.5 p
   2.  9 hr. 15 m.
   3.  9 hr. 33 m. 20 s.


     Notes

  1. Suppose present cost = x pence/litre
       Then previous cost = x - 7
             So 25(x - 7) = 23 x
                 Solving, x = 87.5   

  2. Assume some definite distance between KX and York.
     (We will choose 200 ml.)
     Then speed of each train = 100 mph.
     At 8:30 trains are 150 ml apart, and approaching at 200 mph.
     So time taken to meet = 150/200 = 3/4 hr.

  3. Speed of train from York = 200/2.5 = 80 mph.
     At 9:00 trains are 100 ml apart, and approaching at 180 mph.
     So time taken to meet = 100/180 = 5/9 hr.

A. "At least one of those cars is a Ford."
B. "More than one of those cars is a Ford."
C. "More than one of those cars is not a Ford."

What can you say about the number of Ford cars if:

1. A was correct but B was not?
2. B was correct but C was not?
3. Only one of the three comments was correct?