sjuniv32
What is the remainder when the positive integer x is divided by 7?
1) The remainder is 1 when 3x is divided by 7.
2) The remainder is 1 when 7x is divided by 3.
1) The remainder is 1 when 3x is divided by 7.
Equation: \(3x=7y+1\), where y is quotient and 1 is the remainder.
Check for value of x and y as integers.
y=2: \(3x=7*2+1=15\) or \(x=5\).........
Remainder when 5 is divided by 7 is 5.y=5: \(3x=7*5+1=36\) or \(x=12\).........
Remainder when 12 is divided by 7 is 5.y=8: \(3x=7*8+1=57\) or \(x=19\).........
Remainder when 19 is divided by 7 is 5.So remainder is 5 always.
Sufficient
2) The remainder is 1 when 7x is divided by 3.
Equation: \(7x=3y+1\), where y is quotient and 1 is the remainder.
Check for value of x and y as integers.
y=2: \(7x=3*2+1=7\) or \(x=1\).........
Remainder when 1 is divided by 7 is 1.y=9: \(7x=3*9+1=28\) or \(x=4\).........
Remainder when 4 is divided by 7 is 4.Different remainders.
Insufficient
A