if the volume of a cone is 294.38 and the radius of the base is 7.5 cm . what would be the height of the cone

The volume of the cone is 294.38 . The radius of the base is 7.5 cm . Which of the following could be the height of the cone ? 

$${\mathtt{V}} = {\frac{{\mathtt{\pi}}{\mathtt{\,\times\,}}{{\mathtt{r}}}^{{\mathtt{2}}}{\mathtt{\,\times\,}}{\mathtt{h}}}{{\mathtt{3}}}}$$

$${\mathtt{294.38}} = {\frac{{\mathtt{\pi}}{\mathtt{\,\times\,}}{{\mathtt{7.5}}}^{{\mathtt{2}}}{\mathtt{\,\times\,}}{\mathtt{h}}}{{\mathtt{3}}}}$$                     Times both sides by 3

$${\mathtt{883.14}} = {\mathtt{\pi}}{\mathtt{\,\times\,}}{\mathtt{56.25}}{\mathtt{\,\times\,}}{\mathtt{h}}$$            Divide both sides by 7.5^2 which = 56.25 and pi

$${\mathtt{5}} = {\mathtt{h}}$$  (nearest whole. the actual figure is around 4.998)

The answer is b, 5cm.

The formula for the volume of a cone is V=1/3BH or V= $${\mathtt{\pi}}$$ r^2H, in which B equals the area of the base,H is the height of the cone, and r is the radius of the base.

Plugging in the values, we get 294.38=1/3* $${\mathtt{\pi}}$$ *56.25*H

To solve for H, isolate the variable by dividing both sides by $${\mathtt{\pi}}$$ , 1/3, and 56.25

294.38/(1/3)/ $${\mathtt{\pi}}$$ /56.25 is approximately 5.

The correct answer would be B, 5cm.

Ok, I am probably wrong. Please excuse my low mental capabilities.

No you got the same answer :)

what is the scientific notation for 0.00011 ?

$${\mathtt{1.1}}{\mathtt{\,\times\,}}{{\mathtt{10}}}^{-{\mathtt{4}}} = {\mathtt{0.000\: \!11}}$$

(fyi  $${{\mathtt{10}}}^{-{\mathtt{4}}} = {\frac{{\mathtt{1}}}{{{\mathtt{10}}}^{{\mathtt{4}}}}} = {\frac{{\mathtt{1}}}{{\mathtt{10\,000}}}}$$ )