Solve: 70 + \( \frac{72}{6} \) + 29 − 30
Two pipes, A and B, can fill a tank of 3700 litres in 9 hours and 6 hours, respectively. If they are opened together, how many hours will they take to fill an empty tank of 6400 litres?
\( \frac{1152}{185} \) hours
\( \frac{1149}{185} \) hours
\( \frac{1159}{185} \) hours
\( \frac{1153}{185} \)hours
The arithmetic mean of 25 real numbers is 110. If 10 numbers are increased by 12\( \frac{1}{2} \) each, another 10 numbers are increased by 15 each and the remaining 5 numbers are unaltered, then the new value of the arithmetic mean is: