Final answer:
To determine IQ using Terman's Stanford-Binet Test, the formula MA/CA x 100 is used. The correct distribution for hypothesis testing with a small sample size (less than 30) is the student's t-distribution. The widely used IQ test of today was developed by David Wechsler.
Step-by-step explanation:
The correct formula for determining IQ as used in Terman's development of the Stanford-Binet Test was MA/CA x 100, where MA is mental age, and CA is chronological age. When using this formula, an IQ of 100 is considered average.
Regarding the hypothesis testing question, the correct distribution to use when the standard deviation is known and the sample size is more than 30, or the population is known to be normally distributed, is the Normal distribution. However, if the population distribution is unknown and the sample size is small (less than 30), the Student's t-distribution should be used. Because the sample size is 15, which is less than 30, the correct distribution is the Student's t-distribution.
As for the developer of the most widely used IQ test today, the answer is David Wechsler. He developed the Wechsler Adult Intelligence Scale (WAIS) and the Wechsler Intelligence Scale for Children (WISC), which are among the most commonly used IQ tests in the world.