Standard Deviation Question

Our class just completed our final yesterday. Our teacher is unable to give us individual grades until next thursday. He left us with this information.

76 Students
84.9 Mean
8.6 Standard Deviation

A passing grade for the test was a 70. My question is how many students got below the required 70.

no way to know without assuming a distribution of grades.

Are there any assumptions that can be made based off of the information given without knowing the distribution?