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A necklace is made by stringing N individual beads together in the repeating pattern red bead, green bead, white bead, blue bead and yellow bead. If the necklace begins with a red bead and ends with a white bead, then N could be:
A.16 B.32 C.54 D.68
Read Solution (Total 7)
-
- D. 68
R G W B Y is the bead pattern and it repeats.
Bead want to end with White.
So, the 3rd, 8th, 13th, 18th... beads will be W.
So, number of beads - 3 has to be divisible by 5 for it to be a White bead.
For those conditions, option D(68) only satisfy.
i.e., 68 - 3 = 65 and that also divisible by 5.
S0, 68 is the answer.
- 12 years agoHelpfull: Yes(31) No(6)
- 68
as
no of beads , N = 5x+3
when x=13, N=68 - 12 years agoHelpfull: Yes(19) No(7)
- @jason Could u plz explain why you taking X as 13 and why adding 3
- 12 years agoHelpfull: Yes(14) No(3)
- White bead is used in 3rd Position.....and repeats itself after every 5 beads
Following A.P.........
l=a+(n-1)d
=3+(n-1)5
=3+5n-5
= 5n-2 (its not......5n-3)
For 5n-2 ..........none of the options satisfy because the result is not divisible by 5.. :-
When 5n-3 can't be used...how 68 is the answer ....satisfying the condition......? How can it be ? - 9 years agoHelpfull: Yes(5) No(1)
- Red Green White Blue Yellow---This is arrangement
verify through answers
16 (15th one yellow and 16th one Red so it's fail)
32 (30th one yellow and 32nd one Green so it's fail)
54 (55th one Yellow and 54th one Blue so it's fail)
68 (55th one yellow and 68th one White so it's Success)
- 10 years agoHelpfull: Yes(4) No(0)
- quick solution would be:
Take a sample pattern : RGWBY-RGW [ starts with red and end with white]
total beads :8
u will use two sets to construct this bead pattern(total) : 10
difference would be : 10-8=2
see the options , only 68 holds the condition - 10 years agoHelpfull: Yes(1) No(1)
- Pattern should end with white. So the total number of beads = (number divisible by 5) - (2). Only 68 satisfies the condition. 70-2=68.
- 8 years agoHelpfull: Yes(0) No(1)
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