Elitmus
Exam
Numerical Ability
Sequence and Series
a basketball is dropped from a height of 20 feet.it bounces back each time to a height which is one half of the height of the last bounce.how far approximatesly will the ball have to be travelled before it comes to rest?
A)30FT.
b)40
C)60
d)CANNOT B DETERMINED
Read Solution (Total 9)
-
- 1st time = 20 ft
2nd time = 10ft down + 10 ft up
3rd time = 5ft up + 5ft down
and so on
Total distance travelled = 20 + (10 + 10) + (5 + 5) + (2.5 + 2.5) + . . .
= 20 + (10 + 5 + 2.5 + ...) + (10 + 5 + 2.5 + ...)
Assuming the ball comes to rest at infinity,
Total distance travelled = 20 + [ 10/ (1 - 0.5) ] + [ 10/ ( 1 - 0.5) ]
= 20 + 20 + 20 = 60
- 12 years agoHelpfull: Yes(79) No(6)
- using formula of impact,
when any object is dropped from a height of h1 .it bounces back each time to a height which is h2.the total distance covered by object(it comes to rest)
H= h1*(1+k)/(1-k), where k= squrt(h2/h1)
h1=20, h2=10 ==> total distance H= 3*20= 60 feet. - 12 years agoHelpfull: Yes(20) No(2)
- 20 + 2(10+5+2.5+....)
apply formula of infinite G.P
a/(a+r),where r=1/2
20+2(10/1-1/2)= 60 feet - 11 years agoHelpfull: Yes(15) No(3)
- TOTAL DISTANCE THAT BALL HAVE TO TRAVEL IS
20+10+10+5+5+2.5+2.5+1.25+1.25+.625+.625+.......
20+20+10+5+2.5+1.25+..........
20+(20/(1-1/2))
20+40
i.e
60 - 11 years agoHelpfull: Yes(8) No(1)
- here is a trick if ball drop for 3/4 or 1/2 or smthng like ths... then(1+2)*height.
so we get, according to d question,
(1+2)*20=60 (100 % sure) - 11 years agoHelpfull: Yes(1) No(4)
- it is in the form of gp in which we can use the formulae s=a/1-r+((1/2a)/1-r))
where a=20 s=1/2 - 11 years agoHelpfull: Yes(1) No(0)
- lets assume its a series of nth gp...so first calculate in one direction...
downwards 20(1-12)=40
upwards a=10 half height
10(1-12)=20
so total travelled=60 - 10 years agoHelpfull: Yes(1) No(0)
- cannot b determined becouse we dont know what is the lower level of the bounce ball
- 9 years agoHelpfull: Yes(1) No(5)
- 40(b)
20/3/2=13
20+13+14=40 - 8 years agoHelpfull: Yes(0) No(2)
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