Read twice please, complete and full answer in order to give credit,thanks

Suppose you implemented a quadratic time (that is O(n 2 )) algorithm for a problem P. On a test run, your algorithm takes 50 seconds on inputs of size 1000. Your friend found a clever algorithm which solves the same problem with a running time O(n 3/2 ). However, the faster algorithm takes 150 seconds on inputs of size 1000. How could this be? If you need to solve a problem of size 4000, which algorithm you should use? What about inputs of size 10,000? Explain your answers (assume low-order terms are negligible).