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WWW (Posted on 2006-07-04) Difficulty: 2 of 5
A job opening for a Webmaster has three desirable skills: writing, design, and programming. Of the received applications, 30 have at least one of these skills: 18 know design, 20 can write well, and 23 have programming ability. There are 6 with writing and design skills only, 7 with just writing and programming, and 4 who can design and program but can't write. Only those with all three skills are interviewed. How many interviews are there?

No Solution Yet Submitted by alex    
Rating: 3.3333 (3 votes)

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Solution Solution | Comment 4 of 6 |

The corect answer is 13.

The puzzle can be solved using venn diagram.

Draw 3 intersecting circles and name them as W (for writing), D (for designing) and P (for programming). The 3 intersecting circles will have 7 empty spaces. Name them as follows : a=W only, b=W & D, c=D only, d=D & P, e=P only, f=P & W, g= W, D & P. Thus, we have to find the value of g.

We get the following equations from the problem : b+d+f+g=30, b+c+d+g=18, a+b+f+g=20, d+e+f+g=23, b=6, f=7, d=4.

Substituting the values of b, f and d in the first equation, we get g=13 which is the answer.

  Posted by prasannadatta on 2006-07-17 11:35:20
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