Answer: 90% confidence interval would be (66.92,69.08).
Explanation:
Since we have given that
Number of kittens = n = 35
Mean = 68 days
Standard deviation = 3.9 days
We need to find the 90% confidence interval.
So, z= 1.645
So, intervals would be
![\bar{x}\pm z(\sigma)/(√(n))\\\\=68\pm 1.645* (3.9)/(√(35))\\\\=68\pm 1.08\\\\=(68-1.08,68+1.08)\\\\=(66.92,69.08)](https://img.qammunity.org/2020/formulas/mathematics/college/fhztvrjdov3bc6totue6t1irn11q5rowdn.png)
Hence, 90% confidence interval would be (66.92,69.08).