9090 is 70% of 12,985.7143
Answer:
<em>The mass of the steel ball is 4,235.9 gr</em>
Step-by-step explanation:
<u>Density</u>
The density ρ of a substance is a measure of its mass per unit volume:

If the density and the volume are given, the mass can be calculated by solving the above formula for m:

We know the density of pure steel ρ=8.09 gr/cm3 and the diameter of a solid steel ball d=10 cm.
We need to calculate the volume of the sphere:
The volume of a sphere of radius r is given by:

The radius is half the diameter: r= 10/2 = 5 cm. Thus:

Calculating:

The mass is:

m=4,235.9 gr
The mass of the steel ball is 4,235.9 gr
Answer:
c= 20h + 60
Step-by-step explanation:
The correct dependent variable for this equation is "c" cost of Mr Z's tutoring. The independent variable is "h" hours of tutoring. This is because the independent variable h hours should determine the cost of tutoring c. Therefore the equation can be interpreted: if there are h hours of tutoring which cost 20 per hour, total cost is equal c. Also slope of the equation is 20, coefficient of h.
First, the mark down 15% would make the value 85% of the original, so doing 15.99*0.85 gives you 13.59. Then take that and multiply that by 0.5, because of the half price, to get a final price of $6.79