Solution:

Alpha has Yellow
Beta has Yellow
Gamma has Green
Delta has Red

Explanation:
To solve this problem one must keep in mind that
a) Two are lying and two are telling truth
b) Neither two sides of a card are of same color nor two cards are similar
On trying all the possible combinations while keeping these two situations in mind.

Solution:

Angelina – German and Italian
Brad – French and Italian
Cindy – German and English
Duke – Italian and English

Solution:

120

Explanation:
Let g be the grass in the beginning
r be the rate at which grass grows everyday
y be the rate at which one cow eats the grass per day
n be the number of cows to eat the grass in 96 days

g + 40*r = 40*40*y ------- 1
g + 60*r = 30*60*y ------- 2
g + n*r = 20*n*y ---------- 3

from 1 and 2 we have
r = 10y and g = 120r
using 3, we get
nr=120r
n = 120

Solution:

64

Explanation:
Assume that the number of Woolf’s sons = n
Number of brothers of each son = n-1
Number of sons for each of Woolf’s son = n-1
Woolf’s age = n-1*n-1
Which is equal to a perfect square between fifty and seventy
Which is equal to 64

Solution:

1600m

Solution:

1349

Explanation:
Let number be ABCD

A = B/3
C = A+B => C = 4B/3
D = 3B

=> B=3 , A=1 , C=4 and D=9
1349

Solution:

Gerard:2 & Justin:14

Explanation:
G+2=J-2
Also, 2(G-2) = J+2
Solving both the equations, J=14

Solution:

4 Kg

Explanation:
2% of 100kg = (100 - 50)% of x
2kg = x/2

=> x = 4kg (answer)

Solution:

Payal

Solution:

Equal