# Khan/khan-exercises

### Subversion checkout URL

You can clone with
or
.
Fetching contributors…

Cannot retrieve contributors at this time

125 lines (104 sloc) 8.53 KB
 Negative number word problems
randRange( -20, -1 ) randRange( 5, 30 ) X - Y

{This afternoon, an outdoor temperature had a reading of|On a cold February afternoon, the temperature outside was} abs( X ) degrees below zero. {By evening, the temperature had dropped by|In the evening, you take a quick look at the thermometer, and see that the temperature had dropped by} Y degrees.

What was the temperature in the evening?

Z degrees

abs( X ) degrees below zero is the same as X^{\circ}.

Since the temperature dropped by Y^{\circ}, subtract this amount from the afternoon temperature.

X^{\circ} - Y^{\circ} = Z^{\circ}

The temperature in the evening was Z^{\circ}.

randRange( -30, -15 ) randRange( -10, 20 ) Z - X

{When person( 1 ) went outside to go sledding in the morning|As person( 1 ) prepared for his( 1 ) daily sledding practice}, he( 1 ) {looked at the thermometer and saw|heard on the radio} that the temperature was abs( X ) degrees below zero. {After sledding for plural( randRange( 1, 8 ), "hour" ),|After a long day of sledding he( 1 ) saw that} the temperature was now Z degrees.

By how many degrees had the temperature increased?

Y degrees

abs( X ) degrees below zero is the same as X^{\circ}.

Change in temperature = final temperature - initial temperature

Change in temperature = Z^{\circ} - (X^{\circ}) = Z^{\circ} - X^{\circ} = Y^{\circ}

The temperature had increased by Y^{\circ}.

randRange( 25, 40 ) randRange( 20, 35 ) -X - Y

person( 1 ) was scuba diving X meters below sea level when he( 1 ) spotted a beautiful fish below. {From a distance, the fish looked to be about randRange( 25, 35 ) cm wide. |}{To take a proper photograph|To see the fish up close}, person( 1 ) dove Y meters until he( 1 ) was level with the fish, staring into its eyes.

Where was the fish relative to sea level?

Z meters

person( 1 ) was initially X meters below sea level, which can be written as a negative number, -X meters.

person( 1 ) dove down Y meters, so we can subtract that distance from person( 1 )’s initial level to find out where the fish is.

Fish’s position relative to sea level =-X\text{ meters} - Y\text{ meters} = Z\text{ meters}

randRange( 5, 20 ) randRange( 5, 10 ) Y + X

A spinner dolphin jumped from X meters below sea level and flipped through the air at Y meters above sea level. {The jump itself took about 1.randRange( 1, 9 ) seconds.|}

How many meters did the dolphin travel to reach the highest point of the jump?

Z meters

The dolphin was initially X meters below sea level, which can be written as a negative number, -X meters.

Distance the dolphin jumped = final position - initial position

Y\text{ meters} - (-X\text{ meters}) = Y\text{ meters} + X\text{ meters} = Z\text{ meters}

randRange( 10000, 50000 ) randRange( 10, 50 ) randRange( 100, 500 ) N * COST X - Y

person( 1 ) received a loan of $commafy( X ) from the bank to start a baseball camp. person( 1 ) used the loan to rent baseball bats, mitts, and baseballs for the summer, and to pay the coaches’ salaries. Over the course of the summer, N campers attended person( 1 )’s baseball camp, and each camper paid a fee of$COST to attend. person( 1 ) used all of the money from the campers’ fees to start paying back the loan.

At the end of the summer what was person( 1 )'s net worth, assuming he( 1 ) had no other assets or liabilities?

-1 * Z

person( 1 ) started out the summer with $commafy( X ) of debt, which can be represented as a negative number, -$commafy( X ).

Amount of money person( 1 ) earned from campers = N \times $COST=$commafy( Y )

debt + earnings = person( 1 )'s account balance

-$commafy( X ) +$commafy( Y ) = -\$commafy( Z )