Practicing Success
The average of ten numbers is 32.5. The average of first four numbers is 25.6 and that of the last three numbers is 38.2. The 5th number is 50% more than the 6th number and 8 less than the 7th number. What is the average of 5th and 7th numbers? |
42 41 42.4 41.5 |
41.5 |
Sum of all ten numbers = 10 x 32.5 Sum of First four numbers = 4 x 25.6 Sum of last three numbers = 3 x 38.2 So sum of 5th, 6th and 7th numbers = (10 x 32.5) - 4 x 25.6 -3 x 38.2 = 108 Let's assume 5th number is x then 6th number is \(\frac{2}{3}\)x and 7th number is x + 8 From above, x + \(\frac{2}{3}\)x + x + 8 = 108 x= 37.5 Accordingly, 5th number is 37.5 and 7th number is 45.5 Avg. of 5th and 7th number is = 41.5 |