A rectangular park 60 m long and 40 m wide has two concrete crossroads running in the middle of the park and rest of the park has been used as a lawn. If the area of the lawn is 2109 sq. m, then what is the width of the road?
[A].
2.91 m
[B].
3 m
[C].
5.82 m
[D].
None of these
Answer: Option D
Explanation:
Area of the park = (60 x 40) m2 = 2400 m2.
Area of the lawn = 2109 m2.
Area of the crossroads = (2400 - 2109) m2 = 291 m2.
I got it. Its because. 60 and 40 get multiplies to width and. Since there are two cross roads. There will be a common space for two roads. (width of two cross roads is width^2).
Shreya said:
(Wed, Dec 29, 2010 01:28:16 AM)
My doubt is
60x+40x-x2=291?.
Tanya said:
(Wed, Jan 5, 2011 06:51:42 AM)
Its because the area of 2 roads has come out to be 291m2. Rest of the explaination has been given by prajwal.
Naju said:
(Sat, Jan 8, 2011 06:00:47 AM)
Draw the figure you can c two cross road intersect, so we need to subtract it.
Ayoosh said:
(Wed, Jan 12, 2011 08:12:15 AM)
For all having probs in the 60x + 40x - x^2!!!!
See road is a rect. and they are intercrossing. let the width be x, then for one road area will be 40x and for the other road will be 60x since 60 and 40 will be the lengths of road.
now, we area of roads is 291 m2, so
ar(road1) + ar(road2) - ar(intercrossing)
60x + 40x - x^2 = 291 and then on you can find the ans
Jhola said:
(Thu, Jan 13, 2011 05:20:14 AM)
Very good ayoosh.
Ayoosh said:
(Wed, Jan 19, 2011 11:28:32 PM)
If we dont subtract the X^2 THEN the area of intercrossing will be doubled since its accountd in area of both roads !! thats why we subtract x^2
Sujay Ramesh said:
(Sat, Jan 22, 2011 08:50:54 AM)
Thanks ayoosh. Your explanation is good :).
Nakul Gowda said:
(Wed, Jan 26, 2011 11:30:23 AM)
60x + 40x includes the intersection part twice..so to include the intersection part only once, subtract area of intersection part once, ie, x^2....got it yet..
Nayan said:
(Sat, Jan 29, 2011 02:27:28 AM)
Thnks nakul.
Manish said:
(Fri, Mar 4, 2011 01:44:02 AM)
Thanks ayoosh.
Golu said:
(Sat, Mar 19, 2011 05:24:53 PM)
Why 97 was not taken as answer?
Amrut said:
(Wed, Apr 6, 2011 02:04:33 AM)
thnks ayoosh & nakul
Sana said:
(Mon, Apr 18, 2011 03:24:03 PM)
hey golu..
we have two options for the value of 'x' :
x=97 or x=3;
97 is not chosen as value of 'x' because the width of the rectangular park is only 40 m.
and only the value 'x=3' is less than 40 m.
so, 'x=97' is not possible at all.
Area of the crossroads = (2400 - 2109) m2 = 291 m2.
x2 - 100x + 291 = 0