Answer: 1 hour
Step-by-step explanation:
Let the distance they walked be 
in time 
and the distance they walked be 
in time 
,then
Walking speed=
Riding speed=
Also the total time taken=3 hours
∴
...(1)
Since the total distance= 20 km
∴![d_1+d_2=20\\\Rightarrow4t_1+12t_2=20\\\Rightarrow4t_1+12(3-t_1)=20..............[\text{from (1)}]\\\Rightarrow4t_1+36-12t_1=20\\\Rightarrow-8t_1=-8\\\Rightarrow\ t_1=1](https://tex.z-dn.net/?f=d_1%2Bd_2%3D20%5C%5C%5CRightarrow4t_1%2B12t_2%3D20%5C%5C%5CRightarrow4t_1%2B12%283-t_1%29%3D20..............%5B%5Ctext%7Bfrom%20%281%29%7D%5D%5C%5C%5CRightarrow4t_1%2B36-12t_1%3D20%5C%5C%5CRightarrow-8t_1%3D-8%5C%5C%5CRightarrow%5C%20t_1%3D1)
Thus, the they spent 1 hour time in walking.
Answer:
18/3
Step-by-step explanation:
Took the test
Let the speed for the first 12 mi be x mi/h, the speed for 18 mi was (x+4) mi/h
thus given that
time=distance/speed
the average time will be:
3=(12+18)/(x+x+4)
3=30/(2x+4)
solving for x we get
3(2x+4)=30
6x+6=30
6x=24
x=4 mi/hr
Answer: 12 mi/hr
Answer:
2/7
Step-by-step explanation:
There are 22 (12 + 10) total students in the class. That means that the chance of the first student picked being a girl is 12/22.
Now, we must calculate the chance of the next student to be picked <em>also </em>being a girl - however, there is a trap here! Remember that since a girl has been picked, the total student pool has decreased to 21 and and the total number of girls has decreased to 11. This means the new chance of girl being picked is 11/21.
To find the probability of both these events happening in conjunction, these fractions must be multiplied. 12/22 * 11/21 = 132/462, which simplifies to 2/7.
The slope intercept form is y=mx+b
in this case y=-x
y=(-1)x + 0
so the slope m=-1 and y-intercept which is b is 0
