Which of the following CANNOT be weighed using a balance scale and these unit weights: 2, 4, 7, and 10  Choose one
A) 16  B) 15  C) 18  D) 19  E) 21
A. 13 (can be weighed by keeping weights of 10, 2 and 4 )   B. 15 (cannot be weighed)   C. 17 (can be weighed by keeping weights of 10 and 7 kg)   D. 19(can be weighed by keeping weights of 10, 2 and 7 kg)   E. 21 (can be weighed by keeping weights of 10, 7 and 4 kg)   15
<result>B</result>
Which of the following CANNOT be weighed using a balance scale and these unit weights: 2, 4, 7, and 10