The average height of 50 pupils in a class is250 cm. Five of them whose height is 146 cm, leave the class and five others whose average height is 156 cm, join. The new average height of the pupils of the class (in cm) is __________ .  Choose the correct choice from the following choices:
A) 151 cm
B) 351 cm
C) 241 cm
D) 251 cm
E) 261 cm
Total height = 250 * 50= 
<gadget id="calculator">250 * 50</gadget>
<output>12_500</output>
12500 cm.   New average= [12500 - 5 * 146 + 5 * 156 ] / 50 =251 cm.   ANSWER:251 cm
<result>D</result>
The average height of 50 pupils in a class is250 cm. Five of them whose height is 146 cm, leave the class and five others whose average height is 156 cm, join. The new average height of the pupils of the class (in cm) is __________ .