Total amount spent by manufacturer to makes 750 articles =750*0.60=450 Rupees
Total Selling price at profit of 40%=1.40*450=630 Rupees
He sells 600 articles so, selling price per article = 630/600 = 1.05 Rupees
(i) If he sells 630 articles he will get =630x1.05 = 661.50
The cost price =450
Profit=211.50
Profit %=211.50x100/450=47%
(ii) If he sells 560 articles so he will get = 588
The cost price=450
Profit= 133
Profit %=133x100/588=22.61%