Have you forgotten the area of the top of the frustrum ?

Bob

]]>You're welcome.

So did you get it right? / or if not yet submitted, do you want to post your answer?

Bob

I'm working on the same problem.

Is the answer not 220?

]]>So did you get it right? / or if not yet submitted, do you want to post your answer?

Bob

]]>Welcome to the forum.

The smaller pyramid MNPQE is an exact copy of the larger, just scaled down by a scale factor x 0.5

So its surface area will be scaled down by the length scale factor squared (x 0.25)

So you can calculate its surface area.

Now, if we just wanted the sloping surface area, it would be easy enough to get this by subtraction.

But there's an added complication: you are asking for the area including the top square face of the frustrum.

But you know the length of a side of the base, so you can get the size of the smaller square base, and hence finish off the question.

Hopefully, that's enough of a hint; post back if you need more help or with an answer for checking.

Bob

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