In the figure shown, a large multimode fiber with \( n_{\text{core}} = 1.5 \) and \( n_{\text{clad}} = 1.2 \) is used for sensing. A portion with the cladding removed passes through a liquid with refractive index \( n_{\text{liquid}} \). An LED is used to illuminate the fiber from one end and a paper is placed on the other end, 1 cm from the end of the fiber. The paper shows a spot with radius 1 cm. The refractive index \( n_{\text{liquid}} \) of the liquid (rounded off to two decimal places) is \(\underline{\hspace{2cm}}\). 
Rearrange the following parts to form a meaningful and grammatically correct sentence:
P. a healthy diet and regular exercise
Q. are important habits
R. that help maintain good physical and mental health
S. especially in today's busy world