error propagation help

In physics we were given that the volume of an object is equal to piht(d+t), where h is height, t is thickness and d is the inner diameter. My mean height was 12.82 cm, mean thickness was .5060 cm, mean inner diameter was 7.636 cm. I took 5 samples of each, and the std. deviation i got were .06325, .008944, and .04278 respectively. When dividing each by the square root of 5, to get the std. deviation of the mean, i got .0282, .00399, and .0191 respectively. When calculating the volume, i found it to be 165.92 cm^3. I then used the partial derivative method in which the uncertainty of the volume is equal to the square root of the sum of the partial derivative of each measurement multiplied by the respective standard deviation of the mean squared. When doing so, i found my uncertainty to be 307.95. Did i go wrong somewhere? attached is a photo if that helps http://imgur.com/qqoCyxf