3. What is the value, on the 5th of January, 1910, of a 6% note for $475, dated June 18, 1909? 4. What must I pay on the 8th of December, 1910, to redeem my note for $360, dated February 19, 1910? Interest at 6%. 5. How much is due July 20, 1910, on a note for $725, given October 6, 1909, with interest at 5% ? 6. Find interest of $7685, April 25 to November 11, 1910, at 5%. 7. What is the amount of the principal and interest of $2850 at 5% from July 2, 1910, until December 25, 1910? 8. I took a 6% mortgage of $6000 on February 28, 1910. How much interest shall I receive by November 30, 1911? 9. If you loaned your father $540 at 5%, on March 12, 1911, and he paid it back to you on January 20, 1912, how much must he pay you in settlement? NOTE. — Pupils may pretend that they borrow money from each other and loan money to each other, a note being given in each case, and the interest being computed by both the pupil who loans and the one who borrows. Problems in Interest 1. A man bought a city lot for $2500, paying $1000 cash and giving his note, secured by a mortgage on the property, at 6%, payable in one year, for the balance. How much must he pay at the end of the year to cancel the note and mortgage? 2. A man bought a house for $9500, paying $ 3500 cash, and giving his note (and mortgage) for the balance at 5%. How much a year is his interest? 3. Instead of paying rent of $40 a month, a man buys a house for $6500. He pays $2500 cash and gives his note at 6% for the balance. If his taxes are $70 a year, how much less are interest and taxes than rent? 4. A man who is paying $50 per month rent has $3000 in the savings bank. The bank pays him 4% interest. Can he save money by buying a $7000 house with the $3000 and a 6% note, if taxes are $65 a year, and repairs and other expenses are $80? How much? SUGGESTION.-How much a year is he now paying out in excess of the interest from the bank? How much will he pay out yearly in interest, taxes, and repairs? Which is more, and how much? 5. A man who has $4000 invested in shares of a building and loan association that pays him 5% interest annually rents a flat for $45 a month. Would he save money by buying a house for $6500 with the $4000 and a 6 % note, if all expenses on the house amounted to $175 a year? How much? 6. A bank pays 3% interest on money deposited in it, and loans this money at 6 %. How much does it make in 2 years on deposits amounting to $45,000? 36. A SHORT METHOD OF FINDING INTEREST Money is often borrowed for short periods, say 30, 60, or 90 days, especially at banks. 6% is a very usual rate. In such cases, much time may be saved by observing that The interest of any principal at 6% Find the interest of $720 at 6 % for 90 days. $7.20 3.60 $10.80 NOTE. EXPLANATION. - Since of $720, or $7.20, is the interest for 60 days, $3.60 must be the interest for 30 days, and their sum the required interest. This is called the aliquot part method or the 60-day method of computing interest. 1. I needed the use of $800 for a short time, so I borrowed it for 90 days of a man who was in the business of loaning money. He charged 7% interest. What was the amount of the interest? 2. A man who was building a house borrowed $3600 of a building and loan association at 6%, and gave the association a lien on the house as security. At the end of 95 days he sold the house, and with part of the money paid off the note. How much did it take to pay off the note ? 3. A man bought a building lot for $1200, paying one third cash, one third at the end of 90 days, with 5% interest, and the rest at the end of 6 months, with 5% interest. How much did the lot cost him? PART TWO: EIGHTH YEAR V. PRACTICAL MEASUREMENTS 37. SURFACES A surface is the exterior part of an object and has length and breadth but not thickness. A plane surface is a surface like the top of a desk, a table, or the blackboard. If a straight edge of a board is placed in any direction on a plane surface, all parts of the straight edge will touch the plane surface. A square unit, which is a square a unit long and a unit. wide, is the unit of measure in measuring surfaces. To measure anything we find how many times it will contain the unit of measure. The measure of a surface is called its area. NOTE. Other terms, such as base, altitude, angle, etc., have become familiar through use in former work. 38. AREAS OF PLANE SURFACES The Rectangle 1. Find the area of a rectangle 6 in. long and 4 in. wide. (a) How many square inches are there in the lower row ? (b) How many such rows? (c) Then how many square inches in the four rows or the whole rectangle? 6" |