Verbal Reasoning - Mental Ability Questions

Justification:      

In the first and second statements, the common code digit is '8' and the commmon word is 'good'.

So, '8' means 'good'.
In the first and third statements, the common code digit is '1' and the common word is 'fruit'.
So, '1' means 'fruit'.
Thus, in the first statement, '5' means 'sweet'.

C is the daughter-in-law of A who is the grandmother of F means C is the mother of F But F is the son of B. 

So. B is C's husband. But C, the lawyer. is married to the Doctor So. B is the Doctor. F. the Accountant, will he the non of B and C E is the unmarried Engineer 

So. the other married couple can be that of grandmother of F. i.e, A and D. But D, the Salesman, is married to the Lady Teacher. 

So. D, the Salesman, is the grandfather of F. father of B and the husband of A. the Lady Teacher. 

A is the Lady Teacher 

The problem of pumping out water from the flooded mines provided the need of self-working engine, which led James Watt to invent the same.
Thus, both A and R are true & R correctly explains A.

3000 – 3 = 2997

The kerosene oil sprayed on the water provodes a thin cating and the larvae of the mosquitoes are prevented from coming up to breathe. Thus, they die.
Hence, A is true but R is false.

In the real numbers, zero does not have a reciprocal because no real number multiplied by 0 produces 1 (the product of any number with zero is zero).

Hence, 0 doesn't have any multiplicative inverse.

OKG
Remaining all are not in series
only OKG is in series of(15,11,7)

Here it follows the random difference of '4'.