Emissions of nitrogen oxides, which are major constituents of smog, can be modeled using a normal distribution. Let x denote the amount of this pollutant emitted (in parts per billion) by a randomly selected vehicle. Suppose the distribution of x can be described by a normal distribution with μ = 1.5 and σ = 0.4. A city wants to offer some sort of incentive to get the worst polluters off the road. What emission levels constitute the worst 10% of the vehicles? (Round your answer to three decimal places.)