39.2N
19.6N
14.2N
7.4N
5.1N
Correct answer is B
f \(\alpha\) \(\sqrt{T}\)
\(\frac{f_1}{f_2} = \sqrt{\frac{T_1}{T_2}}\)
\(\frac{250}{350} = \sqrt{\frac{10}{T_2}}\)
\(\frac{5}{7} = \sqrt{\frac{10}{T_2}}\)
\(\frac{25}{49} = \frac{10}{T_2}\)
T2 = \(\frac{49 \times 10}{25} = 19.6\)