When Population variance is unknown and n<30 we use t-test.
x=sample mean, u=population mean, s=sample standard deviation,
In my book and on many online websites i found t-test formula to be t=(x-u)/(s/sqrt(n))
But also on some websites it is given that t=(x-u)/(s/sqrt(n-1))
So, which formula should i use for my exams. Any help about this!