Radius of the first vessel (r1) = 15 cm
Height of the first vessel (h1) = 40 cm
Volume of the first vessel = πr1²h1
= 22/7 × 15 × 15 × 40
Volume of the first vessel = 28285.7143 cm³
Radius of the second vessel (r2) = 20 cm
Height of the second vessel (h2) = 45 cm
Volume = 22/7 × 20 × 20 × 45
Volume of the second vessel = 56571.4286 cm³
Now , given that
The height of the third vessel which contain milk of the given two vessels (h) = 30 cm.
Volume of the third vessel = volume of the first vessel + volume of the second vessel.
∴ 22/7 × r² × 30 = (28285.7143 + 56571.4286)
660r² = 84857.1429 × 7
660r² = 594000
r² = 594000/660
r² = 900
r =√900
r = 30 cm
So, the radius of the third vessel is 30 cm, which will contain the milk which is in the two given vessels.