A person divided an amount of Rs. 100,000 into two parts and invested in two different schemes. In one he got 10% profit and in the other he got 12%. If the profit percentages are interchanged with these investments he would have got Rs.120 less. Find the ratio between his investments in the two schemes.

The correct option is 47:53.

Let the amount invested in the first scheme (yielding 10% profit) be Rs. $x$ and the amount invested in the second scheme (yielding 12% profit) be Rs. $y$.
Since the total amount is Rs. 100,000, we get our first equation:
$x+y=\mathrm{100,000}$ (Equation 1)

In the first case, the total profit obtained from the two investments is:
${\text{Profit}}_1=10\%\text{of}x+12\%\text{of}y=0.10x+0.12y$

If the profit percentages are interchanged, the profit from the first scheme becomes 12% and the profit from the second scheme becomes 10%.
The new total profit is:
${\text{Profit}}_2=12\%\text{of}x+10\%\text{of}y=0.12x+0.10y$

According to the problem, interchanging the profit percentages results in Rs. 120 less profit:
${\text{Profit}}_1-{\text{Profit}}_2=120$

Substituting the profit equations, we get:
$(0.10x+0.12y)-(0.12x+0.10y)=120$
Simplifying the terms:
$-0.02x+0.02y=120$
$0.02(y-x)=120$
$y-x=\frac{120}{0.02}$
$y-x=\mathrm{6,000}$ (Equation 2)

Now, let's solve Equation 1 and Equation 2 simultaneously. Adding both equations gives:
$(x+y)+(y-x)=\mathrm{100,000}+\mathrm{6,000}$
$2y=\mathrm{106,000}$
$y=\mathrm{53,000}$

Substituting $y=\mathrm{53,000}$ into Equation 1:
$x+\mathrm{53,000}=\mathrm{100,000}$
$x=\mathrm{47,000}$

Thus, the ratio of the investments in the two schemes is:
$x:y=\mathrm{47,000}:\mathrm{53,000}=47:53$