The battery lives of a new model of Something phones have a normal distribution. Based on the labora

Question

The battery lives of a new model of Something phones have a normal distribution. Based on the laboratory test results, $15$% of the phones have battery lives greater than $20$ hours and $40$% of the phones have battery lives less than $17$ hours. Find the mean and variance of the distribution.[4]

Accepted Answer

mean =17.6, variance = 5.41

2024 YIJC H1 Q6

2024 YIJC H1 Q6