If each term in the sum of a1+ a2...........+aN is either 7 or 77 and the sum eguals 350 , which of the following could be equal to N
a) 38
b)39
c) 40
d)41
e) 42
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sumatitandon
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equivalent of eqn will besumatitandon wrote:If each term in the sum of a1+ a2...........+aN is either 7 or 77 and the sum eguals 350 , which of the following could be equal to N
a) 38
b)39
c) 40
d)41
e) 42
(7+77+7+77+77.......) = 350
taking 7 common
7(1+11+11+1.....)= 350
1+11+1+11+1 .......= 50
lets say 1 is X times and 11 is y times there fore
eqn reduces to
X+11Y = 50
X = 39 and Y = 1, satisfy above eqn,
39 - 7's
1- 77
therefore IMO C
the numbers can be 7 or 77
all the units digits are 7
the sum is 350
that is the units digit is 0
the sum of 7's will give a units digit of 0, if and only if they are in multiples of 10
only 40, in the answers satisfy this requirement
Ans 40: C
all the units digits are 7
the sum is 350
that is the units digit is 0
the sum of 7's will give a units digit of 0, if and only if they are in multiples of 10
only 40, in the answers satisfy this requirement
Ans 40: C
