If simple interest on Tk. 600 for 4 years and on Tk. 600 for 2 years combined is Tk. 180, find the rate of interest.

A committee of 5 members is to be formed out of 3 trainees, 4 professors and 6 research associates. In how many different ways can this be done if the committee should have 2 trainees and 2 research associates?

5% loss is incurred when Rahim sells a watch for Tk. 1140. At what price should the watch be sold to earn 5% profit?

A bag contains 6 red balls, 11 yellow balls and 5 pink balls. If two balls are drawn at random from the bag one after another, what is the probability that the first ball is red and the second ball is yellow?

$2{\cos }^{2}0 + 3\sin 0 – 3 = 0$ হলে ও এর মান কত? উল্লেখ্য - যে, ও এখানে একটি সূক্ষ্মকোণ।