the pattern is 2, 4, 6, 8, .....
2+4+6+8+10+12+14+16+18 = 90
Thus for the next, there will be 10 red and 10 green. So, there will be 10 more red than green:
x+y = 100
x=y+10
y = 45
x = 55
So, x, or the number of red beads is 55
colored beads are placed in the following order
1 red,1 green;then 2 red,2 green;then 3 red, 3 green; and so on In all,how many of the first 100 beads are red?
1 answer