An interval estimate for the average distance "lifetime" for car tyres was reported to be 34121 kilometres to 38455 kilometres, based on a sample of 66 tyres. The variance of the lifetime was determined from previous studies to be 51124695 kms sqd. What level of confidence can be attributed to this interval estimate? State your answer as a percentage correct to two decimal places.

I know this is a reverse type question but the only examples i've seen how to do this involves being given a true proportion estimated to be between 20% to 30%. I'm not sure how to do my question using that formula as i'm given kilometers rather than percentages. Any help would be appreciated. Thanks.