Answer:
49
Step-by-step explanation:
Let x be unknown number which should be added to numbers 1, 11, 23 to get geometric progression. Then numbers 1 + x, 11 + x, 23 + x are first three terms of geometric progression.
Hence,

and

Express q:

Solve this equation. Cross multiply:

I believe it’s x=2.5 or x=2 1/2 or x=5/2
They are all the same answers in different forms . Hope it’s right
-x + 1/2 = x + 4 1/2
+x +x
1/2 = 2x + 4 1/2
-4 1/2 - 4 1/2
-4 = 2x
x = -2
Study all notes, reread the chapters again. Have someone ask questions on the chapters page by page. This always has worked for me. Plus try to do this again the night before the test. You will be surprised how much you can remember by doing it again the night before the test. Hope this helps.