Charter boat Probability Statistics problem

benjamin8161

New member
A charter boat company of St. Lucia takes tourists on a daily dolphin/whale watch cruise. Their brochure claims an 85% chance of sighting a whale or a dolphin. Suppose there is a 70% chance of seeing dolphins and a 12% chance of seeing both dolphins and whales. Make a Venn diagram. Then answer these questions.

(a) What is the probability of seeing a whale on the cruise?

(b) What is the probability of seeing a whale but not a dolphin?

(c) Are "seeing a whale" and "seeing a dolphin" independent events?

Yes, the events are independent.

No, the events are not independent

EDIT:

I am a sophmore in college trying to understand stats as math has never come easy to me, I have made 2 attempts at this problem with both of them coming back to me with wrong answers

Last edited:

HallsofIvy

Elite Member
Have you made no attempt to do this yourself? Do you know what a "Venn diagram" is? Draw two overlapping ovals, mark one "whales" and the other "dolphins". There are three parts to that Venn diagram now- the region in the "dolphins" set that does not overlap whales, "seeing dolphins but not whales", the region in the "whales" set that does not overlap "dolphins, "seeing whales but not dolphins", and the overlap, "seeing both whales and dolphins", . Since "there is a 12% chance of seeing both dolphins and whales" write "12%" in the overlap region. Since "there is a 70% chance of seeing dolphins" the two parts of the "dolphin oval, that part that overlaps whales and the part that does not must sum to 70%. So the part that does not overlap must be 70%- 12%= 58%. That is the chance of seeing a dolphin but not a whale. Finally since there is a "85% chance of sighting a whale or a dolphin" all three regions must add to 85%. We already have a total of 70% so the remaining region must 85%- 70%= 50%, the chance of seeing a whale but not a dolphin.

Do you know what "independent" means here?

benjamin8161

New member
I have made multiple attempts at this problem, i have made a ven diagram... I feel as if you r trying to belittle me ? idk?....however i do kno wat a ven diagram is. I keep getting the wrong answer when I input it into the online homework assignment & online hw assignments do not give any feedback as to why the answer is wrong, which is why i posted the question on this forum.... thanks for the reply none the less

mmm4444bot

Super Moderator
Staff member
I have made multiple attempts at this problem, i have made a ven diagram... I feel as if you r trying to belittle me ? idk?....however i do kno wat a ven diagram is. I keep getting the wrong answer when I input it into the online homework assignment & online hw assignments do not give any feedback as to why the answer is wrong, which is why i posted the question on this forum.... thanks for the reply none the less
Hello Benjamin:

This is a tutoring web site; we do not provide worked solutions to math exercises.

When you joined the forum, you agreed to follow the guidelines.

The forum guidelines state that you need to show what you tried, when asking for help. You did not show any attempts; therefore, your post makes it appear as if you had tried nothing. This is why the question about whether you're familiar with Venn diagrams is a valid question. If you had followed the guidelines, we would not have asked the question.

So, we are happy to look over your work, but you need to post it first.

You may upload an image of your Venn diagram to our server (search the FAQ for "attach file"). :cool:

benjamin8161

New member
I have made multiple attempts at the problem with no succession with any of them. I can only submit answers so many times until it will not let me submit anymore (3x) I have already done 2 submissions

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benjamin8161

New member
Have you made no attempt to do this yourself? Do you know what a "Venn diagram" is?

Do you know what "independent" means here?
I do know what a ven-diagram is....& yes i do know what independent & dependent mean, I am in stats (math 124) and I do pay attention to my teacher

HallsofIvy

Elite Member
Perhaps it is a language problem. Did you read "https://www.freemathhelp.com/forum/threads/86071-Read-Before-Posting"? You say "I have made multiple attempts at the problem with no succession with any of them. I can only submit answers so many times until it will not let me submit anymore (3x) I have already done 2 submissions" but you did not show your attempt here which is what I was talking about.

benjamin8161

New member
Perhaps it is a language problem. Did you read "https://www.freemathhelp.com/forum/threads/86071-Read-Before-Posting"? You say "I have made multiple attempts at the problem with no succession with any of them. I can only submit answers so many times until it will not let me submit anymore (3x) I have already done 2 submissions" but you did not show your attempt here which is what I was talking about.
I did not read that post I probably should have I just tend to have anxiety when it comes to getting school work done in a timely matter, my appologies I edited my initial post to include extra info however I am unable to see my first submission @ least to my knowledge.

stapel

Super Moderator
Staff member
I did not read that post I probably should have I just tend to have anxiety when it comes to getting school work done in a timely matter, my appologies I edited my initial post to include extra info however I am unable to see my first submission @ least to my knowledge.
Are you just guessing, and that's why you don't have any information other than what you typed on your second attempt? If so, then first you need to try doing the exercise. "Doing" is different from "guessing", and involves active thought and written-down computations. It is this working-out that you've been asked multiple times please to provide.

So, before guessing again, please try this exercise. Then reply with a clear statement of what you thought and what you did. We'll be glad to check your work before you try typing-in again to your online assessment.

Thank you!