Let Purnima's original position from the left be P.
When Purnima shifts to her left by 4 places, her position number from the left decreases by 4.
Her new position from the left = P−4
Given that her new position from the left is 10:
P−4=10
P=14
Purnima's original position from the left end was 14.
Swati was three places to the right of Purnima's original position.
Being to the right means a higher position number from the left.
Swati's position from the left = 14+3=17
Total number of girls in the row = 40
To find position from the right end when position from left is known:
Position from right = Total girls - Position from left + 1
Position from right = 40−17+1
Position from right = 24
Therefore, Swati's position from the right end of the row is 24th.
The answer is Option 3: 24th.