The first working out is correct, z = 3
<span>C. 7x/9y is the correct answer.
</span>
Answer:
The ratio of the intensities is roughly 6:1.
Step-by-step explanation:
The intensity I() of an earthquake wave is given by:
<em>where P: is the power ans d: is the distance. </em>
Hence, the ratio of the intensities of an earthquake wave passing through the Earth and detected at two points 19 km and 46 km from the source is:

<em>where I₁ = P/4πd₁², d₁=19 km, I₁ = P/4πd₂² and d₂=46 km </em>

Therefore, the ratio of the intensities is roughly 6:1.
I hope it helps you!
Adrian can put a total of 1716 combinations in the player.
The formula to be used is as follows:
total combinations = n!/[r! *(n-r)!]
n = number of disks available = 13
r = number of disks that be held = 6
= 13! = (13• 12•11•10•9•8•7•6•5•4•3•2•1)/(6! <span>• 7!)
</span>=1716
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Given,
SP~QP
SR~QR
In ∆SRP and ∆QRP
SP~QP (given)
SR~QR (given)
PR=PR (common)
Therefore,
∆SRP~∆QRP by SSS congruence rule.