A GOLF BALL HAS DIAMETER EQUAL TO 4.1CM. ITS SURFACE HAS 150 DIMPLES EACH OF RADIUS 2MM (0.2 CM) .CALCULATE TOTAL SURFACE AREA WHICH IS EXPOSED TO SURROUNDINGS ASSUMING THAT THE DIMPLES ARE HEMISPHERCAL.  Choose the most appropriate option:	A) 81.62cm2	B) 71.62cm2	C) 61.62cm2	D) 51.62cm2	E) 41.62cm2
the total surface area of the golf ball without considering the dimples is 4*3.14*sqrt(4.1/2).   Due to 150 pits on the surface a there will be a reduction in surface area of ball which will be equal to opening area of the dimples which is 150*3.04*sqrt(0.2). again due to formation of the pits there will be an increase in surface area due to hemispherical concave surface of the pits which will be 150*2*3.14*sqrt(0.2) .So, the total surface area will be 4*3.4*sqrt(4.1)-150*3.14*sqrt(.2)+150*2*3.14*sqrt(.2)=71.62cm2   ANSWER:71.62cm2
<result>B</result>
A GOLF BALL HAS DIAMETER EQUAL TO 4.1CM. ITS SURFACE HAS 150 DIMPLES EACH OF RADIUS 2MM (0.2 CM) .CALCULATE TOTAL SURFACE AREA WHICH IS EXPOSED TO SURROUNDINGS ASSUMING THAT THE DIMPLES ARE HEMISPHERCAL.