L B Foster Interview Questions, Process, and Tips

430
5x5x6 = 150 cube

150 – 20( corner cube) = 130 cube

130 x 3 (side remaining) = 390
20 x 2 (side remaining) = 40
total side remaining = 390 + 40 = 430

343 : 729 :: 125 : ?
7^3 : 9^3 :: 5^3:7^3

2.5 sec

Correct option is C)
Let be students are consider as child
Let the age of child added later be x years.
average age of 12 children =20 years
∴ Total age of 12 children =20×12=240 years
After one more child is added-
Average of 13 children =20−1=19 years
Average age of 13 children =
13
sum of 12 children+x
​

19=
13
240+x
​

⇒240+x=247
⇒x=247−240=7 years
Hence the age of child added later is 7 years.

1

Mohammad Gauri

10 x 27=270

8

It is mentioned the the boat is tied with the rope to the tree. So first one will be crossing the river and the other with the help of the ropes tied to the tree will be able to pull the both back and then he will be crossing the river.

Let numbers be 2x, 3x
Given: (2x)^3 + (3x)^3 = 945
8x^3 + 27x^3 = 945
x = 3
Difference between numbers = 3x – 2x = x
Hence difference = 3

Let the distance between each pole be x m. Then, distance up to 12th pole = 11x m

∴ Speed = 11x22m/s

∴ Time to cover total distance up to 20th pole

= 19x×2411x

= 41.45 s

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