The average weight of 8 people increase by 2.5 kg when a new person comes in place of one of them weighting 75 kg. What is the weight of the new person?

If $$ {x^{2}+3{x}+1=0}$$, then the value of $$ {x^{3}+{1\over {x^{3}}}}$$

If $$ sin(θ+30^0)= {3\over \sqrt { 12} }  $$ then find cos²θ : 

In the triangle ABC, AB = 2 cm, BC = 3 cm and AC = 4 cm. D is the middle point of AC. If a square is constructed on the side BC, what is the area of the square?

50 men took a dip in a water tank 40 m long and 20 m broad on a religious day. If the average displacement of water by a man is $$ {4 m^{3}}$$ , then the rise in the water level in the tank will be:

If price of the table is increased by 25%, then a person can buy 25 table less for Rs 25000. What is the original price (in Rs) of the table?

Six years ago, the ratio of the ages of the two persons P and Q was 3:2. Four years hence the ratio of their ages will be 8:7. What is P’s age?

Assume that
$$\sqrt{3} = 3.605 \ (approximately)  $$
$$\sqrt{130} = 11.40 \ (approximately)  $$
Find the value of
$$\sqrt{1.3} + \sqrt{1300}+\sqrt{0.013}  $$