SOLUTION: 1. a man cover a distance of 6 km at the rate of 4km/h & cover a distance of 4 km at rate of 3km/h . what is his average speed? 2. the average marks obtained by 120 candidate is

Algebra ->  Average -> SOLUTION: 1. a man cover a distance of 6 km at the rate of 4km/h & cover a distance of 4 km at rate of 3km/h . what is his average speed? 2. the average marks obtained by 120 candidate is      Log On


   

Question 725050: 1. a man cover a distance of 6 km at the rate of 4km/h & cover a distance of 4 km at rate of 3km/h . what is his average speed?
2. the average marks obtained by 120 candidate is 35. if average marks of pass candidate is 39 and that of fail candidate is 15 , what is the number of candidate who passed in examination?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
1. a man cover a distance of 6 km at the rate of 4km/h & cover a distance of 4 km at rate of 3km/h .
what is his average speed?
The total distance traveled: 10km
let a = the average speed for the trip
Write a time equation, time = distance/speed
6%2F4 + 4%2F3 = 10%2Fa
multiply equation by 12a to clear the denominators, resulting in:
3a(6) + 4a(4) = 12(10)
18a + 16a = 120
34a = 120
a = 120/34
a ~ 3.53 km/hr is his average speed
:
2. the average marks obtained by 120 candidate is 35.
if average marks of pass candidate is 39 and that of fail candidate is 15, what is the number of candidate who passed in examination?
let p = number that passed
then
(120-p) = number that failed
:
%28%2839p+%2B+15%28120-p%29%29%29%2F120 = 35
multiply both sides by 120
39p + 15(120-p) = 120(35)
39p + 1800 - 15p = 4200
39p - 15p = 4200 - 1800
24p = 2400
p = 100 passed
:
:
You should check these solutions in the original equations.