The average age of 12 students is 20 years. If the age of one more student is included, the average decreases by 1, what is the age of the new student ?
A mixture of 20 kg of spirit and water contains 10% water. How much water must be added to this mixture to raise the percentage of water to 25% ?
A number consists of two digits. The sum of the digits is 9. If 63 is subtracted from the number its digits are interchanged. Find the number .
If p =35, q=79 and r =57 , then
If x =ya, y=zb and z=xc then the value of abc is __
If 2x=2y =4-z then 1x+1y+1z is equal to :
If 0.4×0.4×a=0.4×0.04×b, then the value of ab is :
A wheel makes 1000 revolutions in covering a distance of 88 km. The diameter of the wheel is -