Thread: anybody help me arithmetic problems

1. anybody help me arithmetic problems

1) If there are 1.15 land miles in a nautical mile, how many land miles are there in 10 nautical miles?

2) A trip takes 5 hours in a car moving 40 miles per hour. How long would the trip take in a train moving at 100 miles per hour?

3) It takes Bill 4 hours to do a job. It takes Jane 2 hours to do the same job. How many such jobs could they do together in 4 hours?

Thank you

Sri

2. Appendage?

3. Originally Posted by sri340
1) If there are 1.15 land miles in a nautical mile, how many land miles are there in 10 nautical miles?

2) A trip takes 5 hours in a car moving 40 miles per hour. How long would the trip take in a train moving at 100 miles per hour?

3) It takes Bill 4 hours to do a job. It takes Jane 2 hours to do the same job. How many such jobs could they do together in 4 hours?

Thank you

Sri
1)

$\displaystyle T_{10}=a+9d=(1.15)+9(1.15)=11.5$ land miles

2)

$\displaystyle v=\frac{s}{t}$
$\displaystyle s=vt$
$\displaystyle t=\frac{s}{v}$

Distance travelled$\displaystyle =40\times 5=200$miles

$\displaystyle t=\frac{200}{100}=2$hours

3)

Bill takes 4 hours to do 1 job.
Jane takes 2 hours to do 1 job.
Therefore, Jane takes 4 hours to do 2 jobs.

They takes 4 hours to do 3 jobs.

4. a simpler way of looking at #1 is

1mile 10 miles
_____ x _______
1.15 X

(10)(1.15)
_________ = 11.5
1

5. It's a proportion problem:

$\displaystyle \frac{1.15lm}{1nm} = \frac{xlm}{10nm} \rightarrow$ lm = land miles and nm = nautical miles

Use cross multiplication to get:

$\displaystyle 1.15 * 10 = x$
$\displaystyle x = 11.5$

Proportions

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it takes bill 4 hours to do a job. it takes jane 2 hours to do the same job.how many such jobs could they do together in 4 hoirs?

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