+0  
 
0
105
1
avatar

he positive integers from 1 to 150 inclusive are placed in a 10 by 15 grid so that each cell contains exactly one integer. Then the multiples of 3 are given a red mark, the multiples of 5 are given a blue mark, and the multiples of 7 are given a green mark. How many cells have more than 1 mark?

10

12

15

18

19

idk which one

 May 30, 2021
 #1
avatar+35061 
+1

3 x 5 = 15      so all multiles of 15 are marked with two  = 10

3*7    = 21          all multiples of 21 (105 already marked)    = 6

5x7 = 35            35 70 105  and 140  (but 105  already marked)  = 3            total 19

 May 30, 2021

28 Online Users

avatar