First we will calculate rate of work of rosa and amy.
work done by rosa in time t=t*1/7
Work done by Amy and rosa=t(1/7+1/4.2)
t/7+t/a=t/4.2
t=10.5 hr
Always keep remember those formula or logic belowWork rate × Time to finish the job = 1 job done
Work rate = (1 job done) / (Time to finish the job)
Time of doing the job = (1 job done) / (Work rate)
Answer:
1/19
Step-by-step explanation:
Because this is a positive parabola, it opens upwards, like a cup, and the vertex dictates what the minimum value of the function is. In order to determine the vertex, I recommend completing the square. Do that by first setting the function equal to 0 and then moving the 9 to the other side by subtraction. So far:

. Now, to complete the square, take half the linear term, square it, and add that number to both sides. Our linear term is 6. Half of 6 is 3 and 3 squared is 9. So add 9 to both sides.

. The right side reduces to 0, and the left side simplifies to the perfect square binomial we created while completing this process.

. Move the 0 back over and the vertex is clear now. It is (-3, 0). Therefore, 0 is the minimum point on your graph. The first choice above is the one you want.
Answer:
c
Step-by-step explanation:
according to PEMDAS you should always do whats inside the parentheses first, then you'll multiply the parentheses by 5
The mean would be 5
Reason for this is that the mean is when all data is summed up then divided by how many data points there are
So 4+4+7=15
Then divide by 3 would equal 5
I hope this helps!