I am hoping you can help me with a work problem. If i am missing any information, please let me know and i can provide it. Apologies if my statistical language below is not entirely correct.

Context

I am an engineer working at a quarry which is in a geothermal environment. We need to understand the temperature of each blast hole to determine what explosive product to put in a hole prior to blasting, however it is quite expensive to sample every hole (it requires a thermocouple to be installed and left in each hole). Each blast has approximately 200 holes.

Problem

1. We want to understand what would be the minimum number of blasts (given a 200 hole average for each blast) would we need to collect samples in each hole to gain a statistically significant sample size to be confident (95 and 99%) of the variance in temperature between individual holes

2. How many blasts/samples would we need to determine if we could reduce the sampling rate and by how much (i.e. sample only every 2nd/3rd/4th hole) and be confident we would be within a certain temperature range (e.g. +-5°C) for the holes that weren't measured.

Thanks in advance.