ΔABC is an equilateral triangle in which D, E and F are the points on sides BC, AC and AB, respectively, such that AD ⊥ BC, BE ⊥ AC and CF ⊥ AB. Which of the following is true?

Directions: The bar graph given below shows the spending of family income on various items and savings during 1993. Observe the graph and answer the following questions:

The percent of income spent on food is: 

Find the value of the given expression.

 $$\sqrt { 8+\sqrt { 1681} \ } \ $$

The graphs of x = a and y = b intersect at 

A mathematics teacher calculated the total marks obtained by 35 students of 8th class . The average marks of the students were 72. But 36 marks for Reena was calculated in place of 86 obtained by her. What was the correct average of all the students? 

The sum of the HCF and LCM of two numbers is 680 and the LCM is 84 times the HCF. If one of the numbers is 56, the other is : 

The angles of elevation of the top of a tower as observed from the bottom and top of a building of height 80 metre are 60° and 45° respectively. The distance of the base of the tower from the base of the building is:-

A boat takes 16 minutes and 24 minutes to cover a certain distance downstream and upstream, respectively. If the speed of the boat in still water is 15 km/h, find the speed of the stream.