# Insignificant coefficient in a regression

To simplify the question, for example, the interception, which is Beta 0, is +500 and the predictor X1 being 1, Beta1 being negative 100 and other predictors Xi are all 0. i.e. Y = 500 -100 X1.

The question asks that when the case is X1 = 1 (when I am an asian instead of other ethnicity), then what is the value of Y. As the Beta1 has a P-value much larger than 0.05, which indicates insignificant result, I assume the result of Y be 500 only as Beta should be no different from zero. However, the answer is 500- 100(1) = 400. May I know why my interpretation is incorrect? Thank you very much for your time.