Answer:
Formula for mean in grouped data
= Zfx/ Zf
f = sum of the number of mice
= 35
Frequency = 39 + x
Mean = 7
Fx = 20 + 78 + 112 + 8x + 54
= 264 + 8x
7 = 264 + 8x/ 39 + x
7(39+x) = 264 + 8x
After solving you will get
x = 9
Hope this helps.
Answer:
This question needs a step to step long explanation.

PEMDAS states to do what's in the parenthesis first...

PEMDAS states to multiply 5 by 1 next...

PEMDAS states to subtract 4 by 5 next...

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I hope that helps you out!!
Any more questions, please feel free to ask me and I will gladly help you out!!
~Zoey
4
Hope it’s right
Best luck with your studying