A box weighs 8.5 kg when full of sand and weighs 5.5 kg when it is half filled with sand . Weight of the empty box is

The average of 100 items was found to be 30 . If at the time of calculation , two items were wrongly taken as 32 and 12 instead of 23 and 11 , then the correct average is

Among three numbers , second is twice the first and also thrice the third . If the average of the three numbers is 33 , then the largest number is

The value of tan 315° cot (­ -405° ) is equal to

In Δ ABC , if ∠BAC = 90° and AB = AC , then ∠ABC is

If PQ and PR be the two tangents to a circle with centre O such that ∠QPR = 120° then ∠POQ is

If xy+yz+zx = 1, then the value of (1+y2)(x+y)(y+z) ?

If x = at2 and y = 2at then