Three of the following four letter-clusters are alike in a certain way and one is different. Pick the odd one out.

Which two signs should be interchanged to make the given equation correct?
16 + 3 – 5 x 2 ÷ 4 = 9

Find the greatest perfect square number of 5 digits.

A man earns a profit of 60% when he sells an article at 4/3 of the original selling price. Find the percent profit he makes at original price.

Arun purchased 30 kg. of rice at the rate of Rs. 17.50 per kg. and another Rs. 30 kg. at a certain rate. He mixed the two and sold the entire quantity at the rate Rs. 18.60 per kg. and made 20% overall profit. At what price per kg. did he pruchase the lot of another 30 kg. rice?

Three science classes A, B and C take a Science test. The average score of class A is 83. The average score of class B is 76. The average score of class C is 85. The average score of class A and B is 79 and average score of class B and C is 81. Then the average score of classes A, B and C is

A boat goes from A to B in upstream and come back from B to A downstream taking a total time of 3.5 hours. If the speed of boat in still water is 7 km/hr and the speed of stream is 5 km/hr. Find the distance between A and B. 

Select the most appropriate ANTONYM of the given word.

INTENTIONAL