A) 100 Hz
B) 99 Hz
C) 96 Hz
D) 103 Hz
Correct Answer: B
Solution :
Key Idea: Frequencies of 26 tuning forks will be in arithmetic progression. Frequency of two consecutive forks is 3. \[\therefore \] \[f={{f}_{1}}+(n-1)\] (arithmetic progression) Given, \[{{f}_{1}}=2f,n=26,d=-3\] \[f=2f+(26-1)(-3)\] \[f=75\,Hz\] Frequency of 18th tuning fork is \[{{f}_{18}}={{f}_{1}}+(18-1)(-3)\] \[{{f}_{18}}=2\times 75++17\times (-3)\] \[{{f}_{18}}=150-51=99\,Hz\]You need to login to perform this action.
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