ziyuen wrote:

If \(a≤b≤c≤d\) is \(a≥20\)?

1) \(a+b+c+d=170\)

2) \(5a≥2d\)

stmt-1:If nothing is told whether a, b, c and d are integers, +ve or -ve then this stmt-1 is certainly insufficient.

stmt-2:only given about a and d but nothing about c and d. insuff

stmt-1+2:d <= 5a/2

now test the extreme value that is 20.

d <= 5*20/2

d <= 50

so if a = 20 then all b, c & d has to be 50 for a+b+c+d to be 170.

now if you take any less value of a the sum of b+c+d will not be sufficient to make a+b+c+d to be 170 because for lower than 20 value of a d will be lesser than 50.

this is why a has to be >= 20.

Answer is then C.
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