The following histogram for IQ scores of a sample of 7th gra…

The fоllоwing histоgrаm for IQ scores of а sаmple of 7th graders.  IQ scores are rounded to the nearest whole number   a.    How many classes are there? [answer1] b.    What is the class width? [answer2] c.    How many students had an IQ score that was less than 90? [answer3] d.    How many students had an IQ score that was greater than or equal to 130? [answer4]