MYTUTOR SUBJECT ANSWERS

971 views

There are 20 balls in a bag. The probability is 0.25 of picking a red ball. If one more red ball is added, what is the new probability of picking a red ball at random?

Convert 0.25 into a fraction where 20 is the denominator as there are 20 balls in total in the bag. 0.25 is the same as 1/4 and to convert this to 20 as the denominator multiply both the top and the bottom by 5 so the new fraction is 5/20. As the new ball to be added is red it is within both the numerator and denominator so add one to both to get the new probability of 6/21. Simplify this if possible (although this example 6/21 is the simplest form). As the question has given the original probability in a decimal, convert the fraction to a decimal to get 0.2857.

Alex L. 13 Plus  Maths tutor, GCSE Maths tutor, 11 Plus Maths tutor

1 year ago

Answered by Alex, a GCSE Maths tutor with MyTutor


Still stuck? Get one-to-one help from a personally interviewed subject specialist

532 SUBJECT SPECIALISTS

£18 /hr

Seb C.

Degree: History and Politics (Bachelors) - York University

Subjects offered:Maths, History+ 1 more

Maths
History
English Literature

“Hi Everyone! I'm Seb and I am in first year studying History and Politics, both of which I am passionate about equally!”

MyTutor guarantee

£24 /hr

Emma J.

Degree: Medicine (Bachelors) - Cambridge University

Subjects offered:Maths, Chemistry+ 4 more

Maths
Chemistry
Biology
-Personal Statements-
-Oxbridge Preparation-
-Medical School Preparation-

“Hi! I'm a student on a gap year about to study Medicine at Cambridge. I love the sciences, and hopefully can help you get the grade you want! ”

PremiumIgnacio P. GCSE Business Studies tutor, IB Spanish tutor, A Level Spa...
£36 /hr

Ignacio P.

Degree: Aerospace Engineering MEng (Masters) - Bristol University

Subjects offered:Maths, Spanish+ 5 more

Maths
Spanish
Science
Physics
Further Mathematics
Chemistry
-Personal Statements-

“Author of The 3-Step Method to Achieving (under publishing) - APPLIED NEUROSCIENCE & COACHING FOR EXPLOSIVE RESULTS IN MATH, PHYSICS, SPANISH & MORE!”

About the author

£18 /hr

Alex L.

Degree: Management (Bachelors) - Manchester University

Subjects offered:Maths

Maths

“Top tutor from the renowned Russell university group, ready to help you improve your grades.”

MyTutor guarantee

You may also like...

Other GCSE Maths questions

The normal price of a television is £1200. It is reduced to £970. Work out the percentage reduction. Give your answer to 1 decimal place.

5 students are in a maths class and 10 students are in a physics class. The mean mark of the maths class is 90 and the mean mark of the physics class is 85. Work out the mean mark of both classes.

Factorise x^2 + 3x +2

Explain the general formula for a sraight line?

View GCSE Maths tutors

We use cookies to improve your site experience. By continuing to use this website, we'll assume that you're OK with this. Dismiss

mtw:mercury1:status:ok