Kevin has these four number cards: 3 5 7 and 9. the mean is 6 he takes another card. 3 5 7 9 ‘?’. the mean of the 5 cards is still six. what number is on the new card?

The new number would have to be 6.

Step-by-step explanation:

In order to find the mean you add all numbers and divide by how many numbers you added together. In this case you would add 3, 5, 7, and 9 and divide by 4 to get 6. If the median of the cards is still six you could multiply 6 and 5 because you have 5 numbers. Then subtract 9, 7, 5, and 3 which will give you six.

depends on how many days you are talking about

step-by-step explanation:

the answer is 99.