Step 1: Set up a Venn diagram:
Let FR only \(=a\), TR only \(=b\), ER only \(=c\), FR and TR only \(=d\), FR and ER only \(=e\), TR and ER only \(=f\), all three \(=g\). Total \(a+b+c+d+e+f+g=37\).
Step 2: Translate the conditions:
ER only is double the all-three: \(c=2g\).
TR only is one less than ER only: \(b=c-1=2g-1\).
Ten TR volunteers are also in another project: \(d+f+g=10\); TR total is 17, so \(b=17-10=7\). Hence \(2g-1=7\), \(g=4\), \(c=8\).
FR only equals the FR volunteers who are also in ER: \(a=e+g=e+4\).
Total: \(a+7+8+d+e+f+4=37\Rightarrow a+e+(d+f)=18\). Since \(d+f=10-4=6\), \(a+e=12\), so \(e=4\) and \(a=8\).
Step 3: Totals in each project:
FR \(=a+d+e+g=16+d\); TR \(=17\); ER \(=c+e+f+g=16+f=22-d\) (using \(f=6-d\)).
FR has the maximum number of volunteers (more than ER and TR), so \(16+d>22-d\), giving \(d>3\), i.e. \(d\ge 4\) (and \(d\le 6\)).
Step 4: After the withdrawal:
The 4 volunteers in all three projects each leave one project: one leaves TR, one leaves ER, and the other two leave FR.
FR \(=16+d-2=14+d\); TR \(=17-1=16\); ER \(=22-d-1=21-d\).
Step 5: Test the statements for \(d=4,5,6\):
FR: 18, 19, 20. ER: 17, 16, 15. TR: 16.
(1) ER even: false for \(d=4\) (17). Not necessary.
(3) FR \(>\) ER: \(14+d>21-d\iff d\ge 4\). True always.
(2) TR \(>\) ER: \(16>21-d\iff d>5\). False for \(d=4\), so not necessary.
(4) FR even: false for \(d=5\) (19). Not necessary.
Final Answer:
The correct option is (3): More volunteers are now in FR project as compared to ER project.