A student is trying to identify an unknown substance by finding its density. He finds the mass of a weighing boat to be 2.69 g and the mass of the unknown pieces, including the weighing boat, to be 18.01 g. To find the volume he measured out 25.7 mL of water in a graduated cylinder and then added the pieces to find a new measurement of 32.3 mL

Which of the following is an example of how telecommunication devices people do their jobs? a.) a security guard checks the time using a digital watch. b.) a banker does some quick math using a solar calculator. c.) a nurse uses a digital thermometer to take a patient’s temperature. d.) a construction worker reports in to his office using a cell phone.