Three students used the same ruler to measure the length of a paper clip. The measured values are 5.8cm,5.75cm, and 5.76cm respectively. If the ruler has millimeter markings, what could be the possible reasons for getting the different values?

Large helium-filled balloons are used to lift scientific equipment to high altitudes. what is the pressure inside such a balloon if it starts out at sea level with a temperature of 10.0ºc and rises to an altitude where its volume is twenty times the original volume and its temperature is – 50.0ºc ?