In this task, you need to answer the given multiple-choice question on the general math. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

[Q]: Problem: a rower whose speed is 2.5 km / hr in still water rows to a certain point upstream and back to the starting point in a river which flows at 0.5 km / hr . what is the rower ' s average speed ( in km / hr ) for the total journey ? 
Options: a ) 2.2 , b ) 2.3 , c ) 2.4 , d ) 2.5 , e ) 2.6
[A]: c


[Q]: Problem: the element being searched for is not found in an array of 100 elements . what is the average number of comparisons needed in a sequential search to determine that the element is not there , if the elements are completely unordered ? 
Options: a ) 25 , b ) 50 , c ) 75 , d ) 100 , e ) 125
[A]: d


[Q]: Problem: evaluate : 60 - 9 ÷ 3 × 6 = 
Options: a ) 52 , b ) 18 , c ) 42 , d ) 102 , e ) 36
[A]:
c