rohan2345
Points A, B, C, and D lie on number line, not necessarily in that order. If AC=20, CD=7, and AB=3, which of the following could be the value of BD?
I. 30
II. 24
III. 10
A) I only
B) II only
C) III only
D) I and II only
E) I, II, and III
Attachment:
2019.1.1.numberline.jpg [ 118.56 KiB | Viewed 3626 times ]
Trial and error works.
Describing that trial and error is not so easy.
1) Draw each defined line segment. Note length.
2) For each option I, II, and III:
-- manipulate arithmetically to see whether we can achieve the required length
with the numbers given. If we can do so, almost certainly,
we can arrange the letters to place the BD segment in a way that matches the arithmetic.
-- Length of the line with letters in order? AC + CD = 20 + 7 = 27
Because the Roman numerals do not ask for 27, we know that IF the length of BD is possible,
will have to switch the order of letters.
Given: AC=20, CD=7, and AB=3I) 30
3 + 20 + 7 = 30
BA + AC + CD
B__A______________C_____
DBD = 30See diagram for letters' order with segment lengths and numeric value of letter.
II) 24
(20 + 7) - 3 = 24
AC = 20
A__________________C = 20
CD = 7
A__________________C_____D = 27
AC + CD = 27
We need to subtract 3 from this line segment.
Place B inside.
A___B____________C______D
AB = 3
BD = 102) A___
B___________C______
D See diagram for letters' values.
III) 10
20 (- 7 - 3) = 10
20 - 10 = 10
20 = AC
10 = 3 + 7, and AB = 3, CD = 7
A_________________________________C = 20
We need 3 and 7 to be subtracted from this length.
AB = 3
CD = 7
A___B__________D__________CBD = 10All three values are possible.
Answer E