The pressure at the ice point for a constant-volume gas thermometer is 4.81 x 10^4Pa. While that at the steam point is 6.48 x 10^4 Pa.
What pressure would the thermometer indicate at 50°c?

0 deg C = 4.81E4     pressure at 0 deg

100 deg C = 6.48E4     pressure at steam point

100 deg C - 50 deg C = (6.48 - 4.81) * 10^4 = 1.67E4 Pa

50 deg C = 50 / 100 * 1.67E4 + 4.81E4 = 5.65E4 Pa Just the halfway point between the two given pressures

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