Question

In1999 national vital statistics report indicated that about3.9 % of all births produced twins. Is the rate of twin births the same among very young​ mothers? Data from a large city hospital found only1313sets of twins were born to 434 teenage girls. Test an appropriate hypothesis and state your conclusion. Be sure the appropriate assumptions and conditions are satisfied before you proceed

a) Determine the​ z-test statistic. round to two decimal places

b) Find P-values

Answer 1

Solution :

This is the two tailed test .

The null and alternative hypothesis is

H0 : p =0.039

Ha : p 0.039

n =434

x =13

= x / n = 13 / 434 = 0.03

P0 = 0.039

1 - P0 = 1 -0.039 =0.961

Test statistic = z

= - P0 / [P0 * (1 - P0 ) / n]

=0.03 - 0.039 / [(0.039 *0.961 ) / 434 ]

= -0.99

Test statistic = z = -0.99

P(z <-0.99 ) = 0.1611

P-value = 2 * 0.1611 =0.3222