planks

bblast wrote:what will be the least possible number of planks if 3 pieces of timber 42m, 49m and 63 m long have to be divided into planks of same length.

1>7
2>8
3>22
4>none

answer- c

HCF of 42,49,63 =7;

also total length of timber which is to be divided into planks of same lenght=42+49+63=154;
hence total no. of planks would be 154/7=22 hence C

Factorize 42,49 and 63..

42 = 2 x 3 x 7

49 = 7 x 7

63 = 7 x 3 x 3

Common Factor ( Here there is only one common factor viz. 7, however if there were more than one factors then we consider the HCF as we need the least no. of planks) = 7

42 is 6 x 7
49 is 7 x 7
63 is 9 x 7

Therefore least no. of planks = 6 + 7 + 9 = 22.

Hope this helps.

Factorize 42,49 and 63..

42 = 2 x 3 x 7

49 = 7 x 7

63 = 7 x 3 x 3

Common Factor ( Here there is only one common factor viz. 7, however if there were more than one factors then we consider the HCF as we need the least no. of planks) = 7

42 is 6 x 7
49 is 7 x 7
63 is 9 x 7

Therefore least no. of planks = 6 + 7 + 9 = 22.

Hope this helps.