A) 5
B) 10
C) 7
D) 9
Correct Answer: C
Solution :
(c): Observations: \[{{x}_{1}}+{{x}_{2}}+{{x}_{3}}+{{x}_{4}}+{{x}_{5}}=5\times 7=35\] \[{{x}_{1}}+{{x}_{2}}+{{x}_{3}}=5\times 3=15\Rightarrow {{x}_{4}}+{{x}_{5}}=20\] \[{{x}_{3}}+{{x}_{4}}+{{x}_{5}}=9\times 3=27\Rightarrow {{x}_{1}}+{{x}_{2}}=8\] \[\Rightarrow \,\,\,{{x}_{3}}=35-20-8=7\] You may learn to use this kind of a box way of arranging numbers \[{{x}_{1}}\] to \[{{x}_{5}}\]. It will help you visualize tricky problems.You need to login to perform this action.
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