Problem Solving

The points A,B,C and D are on the number line,not necessarily in that order.If the distance between A and B is 18 and the distance between C and D is 8,what is the distance between B and D??

(1)The distance between C and A is the same as the distance between C and B.

(2)A is to the left of D on the number line.

IMO C. What is the OA?

(1)The distance between C and A is the same as the distance between C and B.

ab =18 cd =8

this indicates that c is midway between A & B (coz A & B cannot be the same pt) so ca = bc =9

however distance between b& d can be 9-8 =1 when order is cdb

& is 9+8 = 17 id order is bcd

INSUFF

(2)A is to the left of D on the number line.

if A is to left of D

from this we cannot infer any thing as B may be towards left of A or right of A also C may be towards left of A or right of it

Not SUFF

Combine:

We have order as ADCB

so BD =17

Ans should be C

Hey Sam!

I think that even though we combine the two condition we have two value.

you mentioned ADCB.
What about ACDB

A is to the left of D and C is the mid-point, then distance between B and D is 1. Therefore, we have two value 1, and 17 even though we combine.

Hi Joseph,
My bad, dont know how I did not evaluate ACDB (I should have written down the combinations rather than mentally working) Yes the ans should be E, Thanks for pointing out.