A starts a business with a capital of Rs. 9,000. B joins in the business with Rs.18,000 after some time. For how much period does B join, if the profits at the end of the year are divided in the ratio of 3 : 1? Choose the correct answer
A) 2 months  B) 6 months  C) 7 months  D) 8 months  E) None of these
Explanation :   Let B joins for x months. Then   A:B = 9000*12 : x* 18000 = 3 : 1   =&gt; 9*12 : 18x= 3 : 1   =&gt; 9*12/ 18x = 3/1= 
<gadget id="calculator">3/1</gadget>
<output>3</output>
3=&gt; 9*4 /18x = 1   =&gt; 2/x = 1   =&gt; x = 2. 2 monthsnswer : Option 2 months
<result>A</result>
A starts a business with a capital of Rs. 9,000. B joins in the business with Rs.18,000 after some time. For how much period does B join, if the profits at the end of the year are divided in the ratio of 3 : 1?