Cups A and B are cone shaped and have heights of 33 cm33cm and 37 cm37cm and openings with radii of 10 cm10cm and 13 cm13cm, respectively. If cup B is full and its contents are poured into cup A, will cup A overflow? If not how high will cup A be filled?

1 Answer
Aug 23, 2016

29.9cm29.9cm

Explanation:

We need to find and compare the Volumes of A and B.
Check first whether they are similar in shape - this would make some of the calculations easier.

Are the sides in the same ratio?
13/10 =1.3 and 37/33 =1.12 " "rArr " A and B are not similar"1310=1.3and3733=1.12 A and B are not similar

Vol_("cone") = (pi r^2 h)/3Volcone=πr2h3

Vol_A = (13^2xx37 xxpi)/3" "and " "Vol_B = (10^2xx33xxpi)/3VolA=132×37×π3 and VolB=102×33×π3

By inspection we can see that Vol A > Vol BVolA>VolB

color(white)(xxxxxxxxxxxxxxxxx)13^2 xx37 > 10^2 xx33××××××××x132×37>102×33

Therefore A will not overflow but we need the height.

The cone formed by the water in A and the whole cone of A are similar in shape.

The ratio of the cubes of the heights is equal to the ratio of the volumes.

color(white)(xxxxxxxxxxxxxxxxx)h^3/H^3 = v/V××××××××xh3H3=vV

h^3/37^3 = (10^2 xx33)/(13^2 xx 37)h3373=102×33132×37

h^3 = (37^3 xx10^2 xx33)/(13^2xx37) = 26,731.95h3=373×102×33132×37=26,731.95

h = root3(26,731.95)h=326,731.95

29.9cm29.9cm