In a long jump qualifying competition, the average jump length of successful competitors was 6.5 meters. The average jump length of unsuccessful competitors was 4.5 meter, and average jump length of all competitors was 4.9 meters. Find the percentage (in %) of successful competitors.
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6.5 - 4.5 = 2.0 4.9 - 4.5 = 0.4 0.4/2.0 = 0.2 = 20%
very confusing, i took % of succesful lengths
right approach.good
okay it's need analyzing. very good
right way to get the accurate answer in less time
Very good and thank you....! :)
let x= number of successful jumper and y = number of unsuccessful jumper
then we have (6.5x + 4,5y)/(x+y) = 4.9
and we will get x = 4y
means 20%
6.5x + 4.5y = 4.9(x+y) , x+y=100, Solve the equations and get the answer
Nice
The Very Basic Solution
Let
N = Total no. of jumps
S = Total no. of successful jumps
Then,
N - S = Total no. of unsuccessful jumps
According to question
Sum of all jumps =
[ 4.9
×
N ]
Sum of all successful jumps =
[ 6.5
×
S ]
Sum of all unsuccessful jumps =
[ 4.5
×
(N - S) ]
⇒
[ 4.9
×
N ] = [ 6.5
×
S ] + [ 4.5
×
(N - S) ]
⇒
S = [ 0.2
×
N ]
Thus
20%
successful jumps.
very good
EASIEST ONE
v good
very gooooooooooooooooooooooooooooooood and simple explanation
good~!!!>.<
Let x = percentage of succesfull competitors.
6.5(x) + 4.5(1-x) = 4.9
Solving this equation give x = 0.2
Thus, x = 20%
This is the most elegant solution in my view. Lots of previous posters get worried about dividing by the totals. The core understanding is that the sum of [the products of length and percentage] equals the total average length.
let total no of competitors be 100 successful of them be X ; unsuccessful are 100 -X ; X 6.5 +(100-X ) 4.5 =100 *4.9 ; 6.5 X -4.5 X =490-450 =40 ; 2 X =40 ; X=20 ;It is for a total of 100 persons so 20%
gud1
suppose the successful is x and the failed is y. 6,5x + 4,5y = 4,9(x + y) 0,4y = 1,6y x/y = 1/4 so, for the successful 1/5 100 = 20% and the failed 4/5 100 = 80%
let x=successful y=unsuccessful ave= 4.9 4.9=(6.5x)(4.5y)/(x+y) (4.9x+4.9y)100=(6.5x+4.5y)100 (49-45)y=(65-49)x 4y=16x 1y=4x 1:4=y:x therefore %=((1/(1+4))100 =20%
(6.5x/100)+((4.5)*(100-x)/100)=4.9 6.5x+450-4.5x=490 2x=40 x=20
Simply (4.9-4.5=.4/(6.5-4.5)=20%
s = sucessful; t = total
6.5s + (4.5)(t-s) = 4.9t
6.5s + 4.5t - 4.5s = 4.9t
s = (0.4/2.0)t
Let number of successful=S and Unsuccessful=U. Then, distance covered by successful and unsuccessful = 6.5S+4.5U and this must be equal to 4.9(S+U) i.e., 6.5S+4.5U = 4.9S+4.9U or, 6.5S-4.9S=4.9U-4.5U or, S=(0.4/1.6)U. Let us divide both sides by (S+U). We get S/(S+U) = 0.25U/(U+S) = 0.25U/(0.25U+U)=0.25/1.25=0.2. If we multiply it by 100 for percentage, we get 20%.
my method was similar to this.explanation is lengthy.once equation is formed,by solving the equation ,gives the answer.
Thanks for all......... please reshare
6.5-4.5=2 4.9-4.5=.4 .4 is 20 percent of 2
Let X were sucessful ,eqation becomes 6.6Xx +4.5(100-x) =100X4.9 By solving we get x =20,so successful are 20 % K.K.GARG,India
20% is the answer.
6.5
x + 4.5(100-x) = 4.9
100, solving this we will get x = 20,
(6.5x +4.5y)/(x + y) = 4.9 or 1.6x = 0.4y and x + y = 1 solving x = 0.2 i.e. 20%
6,5x+4,5y=4,9 , x+y=100%=1
65x+45y=49 , y = 1 - x
65x + ( 45 ( 1- x )) = 49
65x + 45 - 45x = 49
20x = 4
x = 4/20 = 1/5 = 0,2 = 20%
6.5x+4.5y=(4.9)100, x+y=100, (x, y) = (20, 80)
call the percentage of success is y, we have ((6.5y+ 4.5(1-y))/1= 4.9 => 6.5y+ 4.5-4.5y=4.9 => 2y = 0.4 => y= 0.2 or 20%
X = SUCCESSFUL AND Y= UNSUCCESSFUL
6.5X + 4.5 Y = 4.9 (X+Y)
65X + 45Y = 49X+49Y
X= 1/4 Y AND X+Y = 5/4Y
100*X/(X+Y) = (Y * 1/4 )/(Y * 5/4) = 20
we have average jumpers =4.5 succesful jumpers=6.5 unsuccesful jumpers=4.9
then we have 6.5/4.5=2.0 also we have 4.9/4.5=0.4 the total percentage=0.4/2.0=20%
all average of competitor is 4,9 m
x= total competitor who succesful y= total competitor who unseccesful
to solve it, (x(6,5) + y(4,5)) / (x+y) = 4,9
6,5 X + 4,5 Y = 4,9X + 4,9Y
1,6X = 0,4Y
Y = 0,4/2 * 100% = 20%
NOTE : 2 = 1,6+0,4
chal be !!!!!!!!!!!
k(6.5)+l(4.5)=4.9 were k and l are fractions of sucessfull and unsucessfull competers then k+l=1 k(6.5)+(1-k)(4.5)=4.9 by solving we get k=0.2 percentage=0.2*100=20%
actually ,we can know the answer to this, by calculating the % increase or % drop in the ave. jump value of successful &unsuccessful players as, compared to ave. jump value of total players.......................................... like,,,, ave.value of successful players=6.5...................... (1) " " " unsuccessful players=4.5 ...............(2) and,,,,, " " " total players=4.9..............(3) now,,,, (1)-(3)=1.6 & (3)-(2)=0.4............... i.e., let 0.4 =x ,,,then 1.6 =4x .........and 5x=100%.....then x=20%
let x is number of successful competitors having average jump =6.5 m and y is number unsuccessful competitor having average jump=4.5 m.
So the average jump of total competitors =4.9 m will be equal to (6.5x+4.5y)/(x+y)
which gives x/y=1/4.
So the percentage of winning competitor will be=(x/(x+y))*100 %=100/5%=20%
nice!!!!!!!!!!!
Let x be the number of successful competitors and y be the unsuccessful competitors. Note that we are finding x/(x+y)
(6.5x+4.5y)/(x+y)=4.9
65x+45y=49x+49y
16x=4y
4x=y
x/y=1/4
x:y=1:4
Then x/(x+y) = 1/(1+4) = 20%
let x denote the succeful tries. then,
x1+x2+x3+.......+xn=6.5*(n)----------equation 1
and,let y denote the number of unsuccesful tries then, y1+y2+y3+......+ym=4.5*(m)---------equation 2
also, (x1+x2+x3+....+xn)+(y1+y2+......+ym)=4.9*(m+n)-------equation 3
now subtract the sum of equation 1 and equation2 from equation 3, we get,
m= 4 *(n)
where n are succesful total tries and m are unsuccesful total tries.
we have to find, n /(m+n)
which is equal to 20%
bit tough route, but fine!
my solution let x % of successful jumps equation to work on 4.9 ( 100 %)= 6.5x+ 4.5(100%-x) 490%= 6.5 x +450%-4.5x 490%-450%= 2x 40 %= 2x 20%=x
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Let a be the number of successful competitions and b be the failed competitions. Note that we are finding a/(a+b)
(6.5a+4.5b)/(a+b)=4.9
65a+45b=49a+49b
16a=4b
4a=b
a/b=1/4
a:b=1:4
So a/(a+b) = 1/(1+4) = 20%