### Tyneside Average Speed

Weekly Problem 12 - 2006
A van travels from Newcastle to South Shields at 30mph and returns at 40mph. What is its average speed?

### For Richer for Poorer

Charlie has moved between countries and the average income of both has increased. How can this be so?

### David and Goliath

Does weight confer an advantage to shot putters?

# Partial Means

##### Stage: 4 Short Challenge Level:

The mean of a sequence of $64$ numbers is $64$.
The mean of the first $36$ numbers is $36$.
What is the mean of the last $28$ numbers?

If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.