# Tutor profile: Pallabee P.

## Questions

### Subject: Java Programming

Difference in Set and List interface?

Set and List both are child interface of Collection interface. There are following two main differences between them List can hold duplicate values but Set doesn’t allow this. In List interface data is present in the order you inserted but in the case of Set insertion order is not preserved.

### Subject: Geometry

ABCD is a parallelogram such that AB is parallel to DC and DA parallel to CB. The length of side AB is 20 cm. E is a point between A and B such that the length of AE is 3 cm. F is a point between points D and C. Find the length of DF such that the segment EF divide the parallelogram in two regions with equal areas.

Let A1 be the area of the trapezoid AEFD. Hence A1 = (1/2) h (AE + DF) = (1/2) h (3 + DF) , h is the height of the parallelogram. Now let A2 be the area of the trapezoid EBCF. Hence A2 = (1/2) h (EB + FC) We also have EB = 20 - AE = 17 , FC = 20 - DF We now substitute EB and FC in A2 = (1/2) h (EB + FC) A2 = (1/2) h (17 + 20 - DF) = (1/2) h (37 - DF) For EF to divide the parallelogram into two regions of equal ares, we need to have area A1 and area A2 equal (1/2) h (3 + DF) = (1/2) h (37 - DF) Multiply both sides by 2 and divide thm by h to simplify to 3 + DF = 37 - DF Solve for DF 2DF = 37 - 3 2DF = 34 DF = 17 cm

### Subject: Basic Math

Two oranges, three bananas and four apples cost Rs. 15. Three oranges, two bananas and one apple cost Rs. 10. I bought 3 oranges, 3 bananas and 3 apples. How much did I pay? (a) Rs. 10 (b) Rs. 8 (c) Rs. 15 (d) Cannot be determined

It is given that 2O + 3B + 4A = 15 …..(1) 3O + 2B + A = 10…….(2) The answer to this question seems to be cannot be determined as we are given three variables but we can form two equations only. But the question is not asking about the individual price of 3 oranges, 3 bananas and 3 apples but it asks the cost of 3O + 3B + 3A. For that, if we add the two equations, we get 5O+5B+5A=25 O+B+A=5 Therefore 3O +3B+3A = 3×5 = 15

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