25m=2500cm. Area of pencil case=2(πr^2) [top and bottom surfaces]+2πrh [curved surface of the cylinder], where h=17.8cm, r=9.5/2=4.75cm. Total SA of case=2πr(r+h)=2π(4.75)(4.75+17.8)=9.5π(22.55) sq cm.
600 cases have a total SA of 5700π(22.55) sq cm = 128535π sq cm = 403805 sq cm approx.
Area of sheet=2500*150=375000 sq cm, which does not cover the required surface area.
The deficiency is 28805 sq cm (at least).