
Answer:
0.1513
Step-by-step explanation:
mean= 15.4
SD=4.5
P(20<X<28)
P((20-15.4)/4.5 Â < Z < (28-15.4)/4.5)
P(1.022 < Z< 2.8 )
From Z distribution table,
P(Z<2.8)= 0.99744
P(Z<1.022)= 0.84614
P(1.022 < Z< 2.8 )= P(Z<2.8)- P(Z<1.022)
            =  0.99744-0.84614
            = 0.1513