Using the provided tables, please write expressions of relational algebra to answer the following inquiries:

a.) ?What PC models have a speed of at least 3.00?

b.) ?Which manufacturers made laptops with a hard disk of at least 100 ?GB?

c.) ?Find the model number and price of all products (of any type) ?made by manufacturer B.

d.) ?Find the model number of all color laser printers.

e.) ?Find those manufacturers that sell Laptops, but not PCs. ?

f.) ?Find those hard-disk sizes that occur in two or more PCs. ?

g.) ?Find those pairs of PC models that have both the same speed and RAM. A pair should be listed only once; e.g., ?list (i, ?j) ?but not (j, ?i).

The given questions should be answered in Relational Algebra format. For example, answer to question "a" should be written as: PC(model, speed, ram, hd, price)

3.00 <= speed

maker model type model speed hd ram price A 1001 1001 2.66 1024 250 2114 pc 1002 2.10 512 250 995 A 1002 pc 1.42 512 80 478 1003 A 1003 pc 1004 2.80 1024 250 649 A 2004 laptop 3.20 512 250 630 1005 A 2005 laptop 1006 3.20 1024 320 1049 ABBBBCDDDDDEEEEEEEEEEFGH 2006 laptop 1007 2.20 1024 200 510 1008 2.20 2048 250 770 1004 pc 1009 2.00 1024 250 650 1005 pc 1010 2.80 2048 300 770 1006 pc 1011 1.86 2048 160 959 2007 laptop 1012 2.80 1024 160 649 1013 3.06 512 80 529 1007 pc 1008 pc (a) Sample data for relation PC 1009 pc 1010 pc 3004 printer 2001 3005 printer 2002 2003 model speed 2.00 2048 1.73 1024 1.80 512 60 ram hd screen price 240 20.1 3673 80 17.0 949 15.4 549 1011 pc 2004 2.00 512 60 13.3 1150 1012 pc 2005 2.16 1024 120 17.0 2500 1013 pc 2006 2.00 2048 80 15.4 1700 2007 2001 1.83 1024 120 13.3 laptop 1429 2008 1.60 1024 100 15.4 900 2002 laptop 2009 1.60 512 80 14.1 680 2003 laptop 2010 2.00 2048 160 15.4 2300 3001 printer 3002 printer (b) Sample data for relation Laptop 3003 printer 2008 laptop model color type price 3001 true 2009 laptop ink-jet 99 3002 false laser 239 2010 laptop 3003 true laser 899 3006 printer 3004 true 3007 printer 3005 false ink-jet 120 laser 120 3006 true 3007 ink-jet 100 true laser 200 Figure 2.20: Sample data for Product (c) Sample data for relation Printer