Choose the appropriate term for each definition below.

• -Standard normal variable T-curve Probability density curve Chi-square curve Continuous random variable  a curve that (1) is always on or above the horizontal axis; (2) has the total area between itself and the horizontal axis equal to 1.
• -Standard normal variable T-curve Probability density curve Chi-square curve Continuous random variable  a probability density curve that (1) extends indefinitely in both directions, approaching, but never touching, the horizontal axis; (2) symmetric about 0; (3) as the number of degrees of freedom becomes larger, it increasingly looks like the standard normal curve.
• -Standard normal variable T-curve Probability density curve Chi-square curve Continuous random variable  a probability density curve that (1) starts at 0 on the horizontal axis and extends indefinitely to the right, approaching, but never touching, the horizontal axis; (2) is right skewed; (3) as the number of degrees of freedom becomes larger, it increasingly looks like a normal curve.
• -Standard normal variable T-curve Probability density curve Chi-square curve Continuous random variable  a continuous random variable that has the standard normal probability density curve.
• -Standard normal variable T-curve Probability density curve Chi-square curve Continuous random variable  a random variable whose all possible values form an interval.