Answer:
If a sample size is less than ___30_____, the sample size must come from a population having a normal distribution in order to follow normal distribution calculations.
Step-by-step explanation:
By Central Limit Theorem we know that if we have a population with mean μ and standard deviation σ, also for sufficiently large sample size, sample distribution is approximately Normally distributed i.e. the population is normal then this theorem is true even for sample size less than 30.