求助一道gre数学题,请不会的千万不要乱回答,·
ifanintegerisrandomlyselectedfromallpositive2-digitintegers,whatistheprobabilitythattheintegerchosenhas
(a)a4inthetensplace
(b)atleastone4inthetensplaceortheunitsplace?
(c)no4ineitherplace?