For this problem the solution would be like this

Ho: P = 0.23

Ha: P <> 0.23

The sample p ("small" p) = 21/68 = 0.309

The standard error of proportions is SEp = sqrt(PQ/n) where

P = .23

Q = 1-.23 = .77

n = 68

Z = (p - P)/SEp

What if the 23% is not given in the question if we are asked to find the solution without the percentage?? similar to this

A market research company is trying to estimate the proportion of consumers that would consider buying a new product. A random sample of 300 people were asked if they would consider buying this product, of which 90 said that they would.

Please help on this.