Final answer:
Based on the sample of 400 dentists, with 334 recommending the toothpaste, the claim that more than four out of five dentists recommend the toothpaste's ingredients is supported, as 83.5% translates to more than four out of five.
Step-by-step explanation:
The student asked if the consumer-protection group can conclude that the manufacturer's claim that more than four out of five dentists recommend the ingredients in its toothpaste is true, based on a sample of 400 dentists where 334 confirmed their recommendation. To evaluate the claim, we perform a simple calculation to find the proportion of dentists in the sample who recommend the toothpaste:
Proportion of recommendations = Number of positive responses / Total number of responses = 334 / 400 = 0.835
This means that 83.5% of the sampled dentists recommend the toothpaste, which translates to more than four out of five dentists (80%). Assuming the sample is properly randomized and representative of the entire population of dentists, the consumer-protection group can conclude the manufacturer's claim is supported by this sample.