Verbal Reasoning - Mental Ability Questions

We know that, 

1 meter = 100 cms. 

=> 1 meter = 3.28084 feet.

Let 'n' number of days it take to complete.

we know that sum of n number= n/2[2a+(n-1)d]
where a=20,d=1;
n/2[2x20+(n-1)1]=275
n[n+39]=550
n2 + 39n - 550 = 0
 n2+ 50n - 11n - 550 = 0
(n-11) (n-50) = 0
n-11 = 0;
n = 11(Days).

'Hypothesis' is a word that gives a brief explanation of the concepts based on the limited evidence. The word 'theory' is closest in meaning to it.

Commissioned means Authority granted for a particular action or function.

Here, in the given options Dismiss is the only word which is opposite in meaning to commissioned.

Hence, Antonym of  Commissioned is Dismiss.

Here Joystick is the word doesn't belong with the others.

Because Except Joystick all others are Output Devices whereas Joystick is Input Device.

VDU - Visual Display Unit - Monitor to display

Speakers - Output sound

Plotter - used to produce single or multiple colored images.

B is the son of C but C is not the mother of B means C is the father of B A is married to C means A is the mother of B. 

F is brother of B means F is son of A and C. D is daughter of A means D is daughter of A and C

Clearly. from the data available. the wife of E cannot be determined.