Answer:
66.98 db
Explanation:
We know that

L_T= Total signal level in db
n= number of sources
L_S= signal level from signal source.

= 66.98 db
Answer:
22.05 Kg
Explanation:
Apply the formula:
GPE = Gravity . Mass . ΔHigh
2778.3 = 10 . Mass . 12.6
2778.3 = 126 . Mass
Mass = 2778.3/126
Mass = 22.05
I believe it's D. The centripetal force moves away from the center, but the marble stays there due to the string.