1. A demand function for air conditioners is given by:

= 10,000-2

+ 0. 0004 income + 30

-4

. At current average prices, an air conditioner costs 5,000 yen, a fan costs 200 yen, and electricity costs 1,000 yen. Average income is 4,000,000 yen. The income elasticity of demand for air conditioners is closest to: