1.

The average price of five different books b1, b2, b3, b4 and b5 is Rs. 450. The average price of book b1 and book b3 is Rs. 250 while average price of book b2 and book b4 is Rs. 650. Find the price of b5 book.1). Rs. 7502). Rs. 6503). Rs. 5004). Rs. 600

Answer»

Average = SUM of elements/number of elements

Given,

Let the price of books b1, B2, b3, b4 and b5 is B1, B2, B3, B4 and B5 respectively.

The average price of five different books b1, b2, b3, b4 and b5 is Rs. 450 =

Total price of five different books =

= 450 × 5

= 2250

⇒ B1 + B2 + B3 + B4 + B5 = 2250

Given,

The average price of b1 and b3 is Rs. 250 while average price of b2 and b4 is Rs. 650 =

Total price of books b1 and b3 =

= 250 × 2

= 500

⇒ B1 + B3 = 500

Total price of books b2 and b4 =

= 650 × 2

= 1300

⇒ B2 + B4 = 1300

⇒ B1 + B2 + B3 + B4 + B5 = 2250

⇒ 500 + 1300 + B5 = 2250

⇒ B5 = 2250 – 1800

⇒ B5 = 450

∴ The price of b5 book is Rs. 450.


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