Question

The area under the standard normal curve where P(-1.1< Z <1.1) is:

A)0.4332

B)0.7286

C)0.3643

D)0.2420

Answer 1

Ans : (B)

We can use formula

P(-1.1< Z < 1.1 ) = P(Z<1.1)- P(Z<-1.1)

= P(Z<1.1) - P(Z>1.1)

= P(Z<1.1) -(1- P(Z<1.1))

= P(Z<1.1) -1 +  P(Z<1.1)

= 2P(Z< 1.1 ) - 1

= 2* 0.86433 - 1.............value of P(Z<1.1) is from tables of normal dist. one can also use excel function    'normsdist'

Final Ans : 0.72866  

Please let me know if you have any doubts by mentioning them in the comments section.