Find the value za/2 needed to constrict a confident interval with level 87%

The value za/2 needed to constrict a confident interval with level 87% is 1.51

Step-by-step explanation:

At 87% confidence level the z is ,  

α= 1 - 87%

  = 1 - 0.87

   = 0.13

α/ 2 = 0.13 / 2

        = 0.065

Zα/2 = Z0.065

        = 1.51 ( Using z table )

step-by-step explanation:

0 and 5 minutes

step-by-step explanation:

given that one morning eight buses arrive late by the number of minutes given below:

0 8 2 6 9 2 0 7 8

write these in ascending order

0   0 2 6 7 8 8 9

in the afternoon two more buses arrive at the bus stop say by x and y minutes late.

total number of buses = 10

median = average of 4th and 5th after arranging in ascending order

since 4th entry is 6, the values of x and y should be below 6

also given 0 is the mode so either x or y or both should be 0 because then only 0 gets the maximum frequency and hence mode

thus we have

0 0 0 2 6 7 8 8 9 and another unknown entry which is below 6.

since median is 3.5, we have the unknown entry to be 5 only because then only median =( 2+5)/2

thus the after noon buses were late by 0 and 5 minutes.