Concept:A statement is sufficient only if it leads to a unique value of
X. Use the simple interest and compound interest formulas to check each statement.
Explanation:Given: Principal
P=Rs. 2,000, rate
X% per annum, time
T years, and
X is an integer multiple of
T.
Simple interest formula:
SI=100P×X×T.
From Statement I:
SI=2160.
So,
2160=1002000×X×T, which gives
2160=20XT.
Therefore,
XT=108.
Since
X is a multiple of
T, let
X=kT, where
k is an integer.
Then
kT2=108. Multiple pairs satisfy this, such as
(X,T)=(108,1),(54,2),(36,3),(18,6).
Thus, Statement I alone is not sufficient.
From Statement II: Compound interest at
20% per annum for
0.5T years is Rs. 1,456.
Amount after
0.5T years:
2000+1456=3456.
Using
A=P(1+100R)n:
3456=2000(1.2)0.5T.
So,
(1.2)0.5T=1.728=(1.2)3.
Hence,
0.5T=3, giving
T=6 years.
This statement gives only
T, not
X, so it is also insufficient alone.
Combining both statements: From Statement II,
T=6.
Substitute into Statement I:
X×6=108.
Therefore,
X=18%.
Both statements together are necessary and sufficient.
Answer:Both Statements I and II together are required.
Correct option: D. Both Statements I and II together.