general
Maths Puzzle
undefined
A ball is dropped from a height of 15 feet.Every time it rebounces to half of the height. how many feet it travelled?
Read Solution (Total 4)
-
- 45 ft till it stops at ground.
total distance travelled = 15 + 7.5 +7.5+ ......+0.= 15+2*((7.5/(1-1/2))=15+30 = 45 ft. - 12 years agoHelpfull: Yes(5) No(3)
- initially ball travels 15feet.
next, it bounces half of the height (i.e 7.5) , so from ground 7.5 up and 7.5 down , totally 15 .
next, similary 7.5.
the series would be 15,7.5,3.75,......
this series is in G.P , so a=15 r=1/2
sum = a/(1-r) = 15/(1-1/2) = 30.
so , the answer is 15+30 =45. (here, 15 is initially ball traveled from top to ground). - 11 years agoHelpfull: Yes(0) No(0)
- Distance travelled by ball=15+15*(1/2)+15*(1/2)**2+15*(1/2)**3+......
=15*(1+(1/2)+(1/2)**2+(1/2)**3+.....)
=15*(1/(1-1/2))
=15*2
=30 - 6 years agoHelpfull: Yes(0) No(0)
- Acrually it forms a submation equation
Sub(n=1, n= ∞) {(15/n)+ (15/n+1)}
By solving this we will get our ans - 5 years agoHelpfull: Yes(0) No(0)
general Other Question