Arranging the diameter in the ascending order,
1.31, 1.31, 1.33, 1.36, 1.43, 1.47, 1.48, 1.49, 1.49, 1.53, 1.53, 1.53, 1.58, 1.68, 1.69.
There are 15 data entry in the given data set.
The 78th percentile can be determined as,
[tex]15\times\frac{78}{100}=11.7[/tex]Thus, the 12th data entry in the ascending order has 78th percentile. 1.53 is the required diameter.
